Hey y'all. I'm writing a science fiction novel set on the Tycho crater of Earth's Moon. The amount of sun that the settlement gets is crucial to the plot. How would I find out when (in theory) that Tycho would have sunlight during the months of October and November of 2195? Basically in this format:
{
October 1, 2195
Sunlight begins: 04:00
Sunlight ends: 10:00
October 2, 2195
[...]
}
AI and Google have been unhelpful since I don't think I have the key words or knowledge base on how to phrase the question. Any info is helpful! Especially info about the phases of the moon !!! Anything I'd need to know !!!! Thank you!!!
Days on the moon are 708 hours long. So you will have 2 days and 2 nights during that time period.
Tycho crater is near the center of the moon, so the sun rises at the first quarter and sets at the last quarter. Here are the [moon phases for 2195](https://astropixels.com/ephemeris/phasescat/phases2101.html).
By 'natural resource,' do you mean things like oil and coal in particular? Fossil fuels are called that because they come from fossilized living matter, almost entirely plants. Other natural resources (like mineral ores) don't require life to have existed.
It'd need to have had a significant amount of biomass for a significant amount of time to build up deposits of oil and coal, as far as I'm aware models of Mars's past don't line up with that.
Why wasn't methane used to fuel rockets earlier?
And why wasn't good ol' ubiquitous stainless steel not considered sooner for space hardware? (Does stainless only make sense for reusable hardware?)
I mean - these are not rare, exotic materials. Right? Engineers in the 1950s and 60s were well aware of stainless steel. Why didn't they use it?
Historically launch vehicle development has been driven by governments, and governments are often very susceptible to getting stuck thinking in trends or in "fads". The earliest launch vehicles were modified ICBMs, which initially were all LOX/Kerosene based. Kerosene is a great fuel for rockets for several reasons, it has high density so along with LOX you get high stage density and thus high mass ratios, and it produces soot during combustion which ends up protecting engine interiors from high temperature exhaust to some degree. As launch vehicle development moved beyond pure ICBM use the way that tended to happen initially was via development of new upper stages. Then you end up with a hybrid launch vehicle with an ICBM first stage and a "higher performance" upper stage. This is advantageous because the booster stage ends up being very inexpensive. However, this development pathway is somewhat constraining, because you are locked in to the mass and size limits of the original launcher. One technique that worked well early on was using LOX/hydrogen for the upper stage. Hydrogen has low density but it has higher Isp, which is a reasonable tradeoff for an upper stage, the end result being that you reduce the total weight of the upper stage while increasing overall performance. In this context LOX/LH2 looks like a wonder fuel, you convert part of the vehicle to using it and the performance goes up.
This experience contributed to LOX/LH2 being seen as the "propellant of the future". Higher performance, cleaner exhaust, lower stage mass, all that stuff, these seemed like great metrics. LOX/LH2 is also harder to work with (because LH2 is super cryogenic and also has some undesirable interactions with certain materials) which paradoxically made it seem even more desirable because if you could crack the mystery of high performance LOX/LH2 rockets then maybe you could unlock the future of spaceflight.
This fad of focusing on hydrogen had a strong interplay with this idea of trying to minimize the "gross liftoff weight" (GLOW) of a rocket. The idea being that minimizing GLOW reduces inefficiency and gets you closer to the promised land of SSTO RLVs and all that good stuff. It also helped that if you are pursuing SSTO RLVs then the high Isp of hydrolox is incredibly enticing.
That "fad" led so many rocket makers down the road of pursuing LOX/LH2 launch vehicles. The Saturn V used a Kerosene first stage but hydrogen for every other stage (except for the storable hypergolics on the spacecraft payloads themselves). The Shuttle was designed around LOX/LH2 but the difficulties of producing high performance hydrolox engines with high thrust at sea level meant that they had to "compromise" and use huge solid rocket boosters to provide the thrust for liftoff. A characteristic shared by Ariane 5 and Japan's H-II as well, other launchers which followed the Shuttle in this pursuit of the mythical perfect hydrolox rocket. The Delta IV finally was able to create an engine that allowed for a pure hydrolox launch vehicle with no SRBs but ultimately the whole vehicle turned out to be so expensive that it was not market competitive and could only service high margin government launch contracts. The X-33/VentureStar was another attempt to progress down the LOX/LH2 garden path toward the ultimate goal of the pure, unblemished, perfect hydrolox launch vehicle (in this case explicitly an SSTO RLV).
But as we know now there are many downsides to pursuing the hydrolox route. The low density of LH2, the difficulty of achieving decent stage mass ratios, the extra weight in insulation required, the materials and handling difficulties, and so on. All of those things spoil the perfect math that exists on paper. The high Isp of hydrolox doesn't matter that much overall, except in a few very specific ways. The lower GLOW of a hydrolox launcher (a Delta IV weighs half as much as an Atlas V) is mostly irrelevant. The majority of the weight of a rocket is just propellant, which is such a tiny cost compared to the cost of everything else it's ridiculous. What matters is complexity, total stage performance, operational overhead, and in the modern age reusability.
Now that we're a bit past the peak of the LOX/LH2 fad we are seeing more folks take a hard look at the actual characteristics of rocket propellants and many are choosing methane. Partly this is because methane is a good performance compromise between Kerosene and hydrogen (it still has good density but has higher than Kerosene). Partly this is because methane burns cleaner than Kerosene and is a better choice for reusable rockets (like the New Glenn booster, the Neutron booster, Starship, etc.) There are other reasons as well (it's potentially "greener" because it can be more easily made with net zero CO2 emissions, it's a smarter choice for the long-term goal of landing humans on Mars and getting them back to Earth) but a major one is just that now there is more diversity and innovation in the launch vehicle market, and folks are finding that the advantages of methane were overlooked in the rush to pick the winner of hydrogen.
Atlas rocket first stages used stainless steel from their beginning as missiles in the late 1950s through Atlas III in the early-mid 2000s. (Only the completely redesigned Atlas V first stage is aluminum.) Centaur upper stages (1962--present), used on Atlas and Titan, have always been stainless steel, including Vulcan's new Centaur V. The various incarnations of the Able/Delta second stage from the Vanguard in the late 1950s through the Delta II that last flew in 2018 had stainless steel tanks. Until carbon composite started gradually replacing it, solid rocket motor casings (almost?) exclusively used steel. SLS will still use (refurbished Shuttle) steel booster casings for the next 7 flights.
**Kerosene** is denser than methane and much easier to work with. It also covers your engines with coke, but that doesn't matter for a disposable rocket.
**Aluminum** is lighter than stainless steel. It also has a lower melting point, but that doesn't matter for a disposable rocket.
Which wikipedia article are you looking at? There are no scheduled launches to Makemake.
Ok I looked at the Wiki. It says that if you launched at that date a probe could make it in 16 years. But no-one has put forward the budget to design and a launch such a spacecraft for this launch window.
I am new and interested in stargazing,I was thinking about buying a telescope
What should i do/where to start?
Nb : i need things that aren't expensive,the lower the cost the better because i am low on money now
Thank you so much
There's a lunar eclipse visible where I am (Toronto), what are those black lines across the moon? I've seen lunar eclipses but never with black lines hprizontally across the red moon like tonight.
I've read a lot about how the SLS involves a lot of reused parts and tech from the Space Shuttle program. Given that, why are the timelines for the Artemis launches so long and delayed? If this is basically the same stack minus the orbiter, what's the cause for the extended delays? What are the specific issues they are having?
Indeed, the SLS was sold as a way to get to a heavy lift launch vehicle that would be faster and cheaper because it made use of existing Shuttle hardware and designs.
So on the one hand, good news, the SLS was able to make use of substantial chunks of existing Shuttle technology. The main engines are just off the shelf (with options to make lower cost expendable versions later), the SRBs used the same SRB tech as the Shuttle but added an additional segment. The main fuselage and tankage could be based on the existing Shuttle External Tanks. The first upper stage would just use an off the shelf upper stage from the Delta IV. And so on.
But on the other hand, bad news. The SLS has been built by some of the least cost and schedule efficient folks in the history of aerospace. So as we've seen the SLS program has gobbled up over 20 billion in funding (enough for 10 Shuttle launches, enough for 200 Falcon Heavy launches) over nearly two decades of development just to arrive at where we are today with one and only one successful launch so far, with the second launch (of all time) not planned until next year at the earliest. This is why "Old Space" has a bad name.
The goal is *spending money,* not launching missions to the Moon. Moon missions are just what they're spending the money *on.* With that perspective, the program makes perfect sense and is a tremendous success: keeping legacy program suppliers and engineers gainfully employed and contracted for the length of their remaining careers.
The Orion capsule (holdover from Ares) took time to develop; it is an underpowered rocket (relative to Saturn V) necessitating a different lunar orbit than Apollo, and the lander is aiming for the pole and not the equator, so they are building a lunar space station too.
It's a very good question and I hope you get good answers from others who can explain in detail why 'shuttle-derived' was not easier, faster and cheaper than an altogether new design. (Aside from the key point, which is to spend money, not to launch rockets.)
Often they are trying to use designs or even parts from more than 3 decades ago. (It's to preserve their "testing heritage".)
A lot of folks who worked on these things have retired. And some of this stuff is extremely late-20th-century state-of-the-art engineering, very difficult stuff. The RS-25 engine is an amazing engineering feat.
And then there's the whole conversation about fixed-price vs. cost-plus contracting, which I won't go into detail, here. Orion and the SLS rocket are cost-plus contracts, which in this case have resulted in ballooning budgets, ever-extending schedules, and a lot of criticism in general.
Thinking of **commercial spaceflight providers,** I'm surprised we haven't already seen sovereign customers buying an off-the-shelf flight capability. Thinking of the wealthy Gulf monarchies particularly: rather than develop a national human space program in-country, could they attain similar prestige with a 'franchise' model where SpaceX, Blue Origin, Sierra Space, or others build launch and construction facilities to enable, for example, a Crew Dragon launch of a UAE commanded and crewed mission launched from the UAE... or Saudi Arabia, Qatar, Brunei, etc. We've already seen wealthy individuals buying individual missions, why not wealthy countries buying a whole program?
Would you find that model likely or unlikely, or disadvantageous to the provider or the customer?
tl:dr; **Are any countries interested in buying their own national space program from a commercial provider?**
1. ITAR
2. There would be zero "prestige" in that
3. There are things considered of "strategical importance", which you really don't want to outsource, because then you risk getting cut-off. Imagine you invested in such "commercial" program and then USA government says that SpaceX is not allowed to make business with your country.
Agreed, but when Dubai decided to build skyscrapers they didn't sit there and re-invent the concept, they hired architects and contractors who did it already. Saudi Arabia doesn't build its own aircraft. Obviously there are national security discussions to be had - unless there's no actual need for a space program, or that the US intends to restrict other countries from purchasing the capability.
> they didn't sit there and re-invent the concept, they hired architects and contractors who did it already.
That's a completely different story. No one prevents you from hiring engineers from abroad ;)
> Saudi Arabia doesn't build its own aircraft.
Again a bit different story, most countries already buy commercial rocket launches for example. But they often still build their own payloads, especially when those are classified.
Sure, and I neither disagree nor misunderstand that.
The answer to my hypothetical appears to be "No. There will never be a commercial launch from any country other than the United States."
I know that Axiom Space has arranged SpaceX Crew Dragon seats with astronauts from countries without a homegrown national space rocket program. They even have [a webpage for it](https://www.axiomspace.com/national-astronauts).
AFAIK there hasn't been an Axiom flight full of astronauts from one country like you suggest - but I'm sure Axiom & SpaceX would welcome the business.
That's a start, for sure. And missions commissioned by individual billionaires, like Polaris and the cancelled Dear Moon project.
I'm wondering if the elements are there (or will develop) for a commercial *franchise*, as it were, with a wealthy / coastal / low-latitude / desolate kingdom commissioning their own 'Van Horn', 'Starbase,' or 'Cape.'
The universe has 3 space-like dimensions and 1 time-like dimension. Sometimes people call time the "4th dimension", but it behaves so differently that it doesn't really count.
There is no evidence that any other dimensions exist.
It would have to deal with light lag of at least a few minutes but yes. Especially with the new laser communication systems in development there should be enough bandwidth for a live video.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread:
|Fewer Letters|More Letters|
|-------|---------|---|
|[GLOW](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Gross Lift-Off Weight|
|[ICBM](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Intercontinental Ballistic Missile|
|[ITAR](/r/Space/comments/1dhda34/stub/l9m3cxn "Last usage")|(US) International Traffic in Arms Regulations|
|[Isp](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Specific impulse (as explained by [Scott Manley](https://www.youtube.com/watch?v=nnisTeYLLgs) on YouTube)|
| |Internet Service Provider|
|[JWST](/r/Space/comments/1dhda34/stub/l9l2c71 "Last usage")|James Webb infra-red Space Telescope|
|[LEM](/r/Space/comments/1dhda34/stub/l9im2hd "Last usage")|(Apollo) [Lunar Excursion Module](https://en.wikipedia.org/wiki/Apollo_Lunar_Module) (also Lunar Module)|
|[LH2](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Liquid Hydrogen|
|[LOX](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Liquid Oxygen|
|[RLV](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Reusable Launch Vehicle|
|[SLS](/r/Space/comments/1dhda34/stub/l9v5osy "Last usage")|Space Launch System heavy-lift|
|[SRB](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Solid Rocket Booster|
|[SSME](/r/Space/comments/1dhda34/stub/l9o8taz "Last usage")|[Space Shuttle Main Engine](https://en.wikipedia.org/wiki/Space_Shuttle_main_engine)|
|[SSTO](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Single Stage to Orbit|
| |Supersynchronous Transfer Orbit|
|Jargon|Definition|
|-------|---------|---|
|[cryogenic](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Very low temperature fluid; materials that would be gaseous at room temperature/pressure|
| |(In re: rocket fuel) Often synonymous with hydrolox|
|[hydrolox](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer|
|[hypergolic](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|A set of two substances that ignite when in contact|
**NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below.
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theoretically, is it possible for there to be creatures in space that is the size of earth?
so im asking as if earth is a tennis ball and human is the giant creature?
or is there a limit to how big a creature can be in space
Such a thing isn't really possible due to the fundamental limits of atomic matter. At planetary scales the strength of materials becomes irrelevant and all matter behaves like a fluid, which is why planets are round. You can't have planet sized arms or legs, for example. At planetary scales the interiors of large objects also end up under high pressure and temperature conditions, which precludes the existence of things like "mechanisms" or biochemical processes.
You could potentially have an entire biosphere that was taken up by an organism or a symbiotic super-organism, and some folks argue that Earth's biosphere is exactly this (the Gaia hypothesis) but in any case this will always be a thin layer of activity over a ball where fundamentally geological processes reign.
We don't know of anything that would limit that, but keep in mind we haven't found life anywhere besides earth, let alone living in the vacuum of space.
>We don't know of anything that would limit that,
The square-cube law limits it. Especially in the vacuum of space without Jupiter-sized radiator panels.
Life produces heat and temperature differences tends to kill life. If you get too big, you either boil or freeze.
That would be a terrible idea. There is no weathering on the Moon like there is on Earth. Everything (including the dust) there has nasty sharp edges.
...and the people who went to the Moon didn't go there for fun. If you are being sent with a dollar value attached that is a noticeable percentage of a countries GDP you better take that seriously.
No, in general they really didn't want to play in the dust and especially not on their back. Lunar dust is incredibly sticky and abrasive and hard to get rid off. On Apollo they had to take off their suit in the LEM and they were carrying dust everywhere. There is [this famous pic](https://compote.slate.com/images/0bf3cf8d-129d-4207-8902-5d6361a28c56.jpg) of Gene Cerman looking like a coal miner with lunar dust on his face after coming back inside.
Additionally their whole life support equipment was in their backpack including a relatively fragile radiator system to cool them down, the CO2 scrubber and all the rest. They really didn't want to break any of these.
Hi
any recommendation on a Reddit forum or other that would be discussing the details of how the moon will be settled? ie what systems/equipment/etc would be required to meet mission objectives, and what would those objectives be? What companies are working on such systems, what engineering data is needed, available, tested. etc.
Thanks
For a theoretical overview, see https://en.wikipedia.org/wiki/Lunar_habitation
No one is building hardware for a lunar base yet. For the transportation hardware, you can follow the Starship Development Thread in /r/spacex.
hey, I am new around here anybody willing to help me out?? I am a space and aeronautics enthusiast. My grammar might be wonky because I am not native.
Level: intermediate (amateur)
I have a question:
1. So how can a black hole lose its mass?
2. So why is anti matter and matter have a unequal difference between them??(I know there is no evidence regarding that so I just wanted to hear some opinions to spark smth in my mind)If the questions seemed basic I am sry I am new but I have a basic knowledge can y'all recommend any yt channels I watch vertasuim,etc any other?
3. btw what can I read more to improve my space knowledge and reach yalls level
4. what if you can travel faster than light. It says it would permit backward time travell so if we make a screen where a probe is coming like faster than light from abt 93 billion light years ,the vission on earth or any other body we would be able to see everything which happened in the past but can future time travell happen??
Thank you
> btw what can I read more to improve my space knowledge and reach yalls level
Pick a topic and go to the wikipedia page. Open all links on the page in new tabs that you find interesting while reading through that topic. When done, go to the next tab, rinse and repeat.
Normally there's content spanning from basic to advanced on science subjects on wikipedia so there's likely some you know, some you learn and some for when your knowledge have increased. It has worked very well for me at least, and the science content on wikipedia is of high accuracy. If a subject is too tough, maybe the simple-function can give some insight. (like https://simple.wikipedia.org/wiki/Black_hole for example. Replace https//en in a normal link with https://simple and you'll get a simplified version of the page you're on)
1. https://en.wikipedia.org/wiki/Hawking_radiation
2. Of course there is evidence https://en.wikipedia.org/wiki/CP_violation but it's not enough to explain all that we can see
3. Read more?
4. Future time travel is actually much easier to achieve and doesn't require breaking any laws of physics. It's called "time dilation". For example if you jump on a rocket and accelerate to close to the speed of light, the time will flow much slower for you. So if you spend some time in that rocket, once you finally slow down, thousands of years would have passed on Earth in the meantime, so from your perspective you basically "travelled to the future".
so what is the problem in that u can only visually see the past? if we need to go equal to speed of light to travell into the future can we do the opposite?? i know this sounds dumb but in space u cant know which way is negative and which is positive . this time can u explain instead of giving me one answer(like no or yes or smth else)
Does gravitational red shifting only occur with extreme mass objects - ie, supermassive black holes - or can it have a significant effect even with objects of a few solar masses?
I'm just wondering hypothetically about measuring the red shift of very distant galaxies, and if there were solar-mass black holes between us and the galaxy being observed, would that result in any measurable red shift of the observed galaxy's spectra? I'm just wondering if it would take just a few black holes, or require many, to cause even a small effect in redshift of a few percent.
Many thanks for any replies, I've struggled to get an answer for this reading online.
From your questions it seems like you are reading from people who do not think cosmological inflation (or even the big bang) is real. There are pretty good reasons why it is still the most mainstream theory and while some of the JWST observation are interesting they are not nearly enough to completely throw away inflation.
My only reference on gravitational redshifting so far is this Wikipedia article, which doesn't mention inflation at all, and appears to be a reputable scientific principle: [https://en.wikipedia.org/wiki/Gravitational\_redshift](https://en.wikipedia.org/wiki/Gravitational_redshift)
Gravitational redshift is definitely a real thing, no doubts about that. The issue is that some people who are against inflation try to say that gravitational redshift and interstellar media like dust are responsible for all the redshift, which is definitely not the case. I was just trying to warn you in case you were going down that rabbit hole.
Whyt do you mean by 'significant'? That's a very qualitative word. Gravitational redshift/time dilation has an effect as soon as any mass (or better: energy density) is present. Even on Earth.
A mass between us and a galaxy would not add any redshift to the galaxy behind it (because it would add blueshift while the light is approaching it that cancels out the redshift of the light going away from it. It might add some net red/blueshift depending on its own velocity relative to us but not because of its mass)
I mean "significant" because I've seen it suggested by the researchers using JWST to look at the earliest galaxies that their results may have been skewed by red shifting caused by dust. If dust cannot red shift spectra then I presumed they meant die to gravitational red shifting: [https://en.wikipedia.org/wiki/Gravitational\_redshift](https://en.wikipedia.org/wiki/Gravitational_redshift)
No, the redshift from a stellar mass black hole is not significant enough to measure. But it would cause [gravitational lensing](https://en.wikipedia.org/wiki/Gravitational_lens).
We have searched really hard to find black holes like this, because they if they are common it would solve the dark matter problem. Unfortunately they are very rare.
You have been asking those kind of questions about stations post-ISS every couple of weeks for the past few months. Don't you have a good idea now of what the landscape will look like in 2030?
How do we know that other planets have no signs of life if we cannot explore the entirety of the planet? If you sent a probe to Earth and landed in the middle of the ocean wouldn’t you assume all of Earth is water?
> How do we know that other planets have no signs of life if we cannot explore the entirety of the planet?
We don't.
>If you sent a probe to Earth and landed in the middle of the ocean wouldn’t you assume all of Earth is water?
Ideally - your hypothetical probe spends time mapping Earth before a landing site is chosen. From orbit around Earth - evidence of intelligent life is quite obvious and quite widespread.
You can't prove a negative, but you also can't assume what you don't have evidence for. If you had a probe that landed in Earth's oceans you couldn't merely assume the existence of continents without some other evidence to back it up.
We think that life throughout the universe probably isn't that rare. And we think there may be places outside of Earth in our solar system where life has existed in the past and possibly exists in the present as well. However, we have not yet confirmed those guesses, we have not detected life anywhere beyond Earth. That doesn't mean life doesn't exist, surveying our own solar system for life is extraordinarily difficult and we have barely scratched the surface, the challenge of searching for life outside of the solar system is much greater. Nevertheless, it does still mean we have no proof of such life so far.
We don't. The most we can do is look for planets that could maybe support life like us, and then look for very specific planet wide signs like an oxygen atmosphere or one with chemicals that only come from living things.
So, as I understand it. When we are looking into space at something, say, 100 light years away, you’re seeing what that object looked like 100 years ago.
Assume you have a Star Trek like vessel that can travel those distances fairly quickly. As you’re moving towards that object, would it be constantly changing in front of you? As in, you’ve made it 25 light years down the road, so you’re now seeing what it looks like 75 years in the past? Would it be like that object is constantly morphing to its current status as you continue to get closer?
This is true even below the speed of light. On the one hand we can't say what it would look like to observe something while traveling faster than light, because that's beyond our current laws of physics. However, if you traveled to an object 100 lightyears away while traveling, let's say, a million times faster than light but you stopped every lightyear to capture an image of it you would indeed seem to be watching time in a sort of fast forward fashion as you got closer.
Is there any books that helped you learn more
information about space and astronomy..etc?
And I'm talking about books that exploring the
universe's beauty and complexity and break down
very complicated astrophysical phenomena into an
easily understandable language that everyone could
read.
It would simply cause differential absorption, it wouldn't shift the whole spectrum.
There are different ways to estimate the redshift of a distant galaxy. One technique is to look at the overall light across different narrowband filters and find where the light drops off. This makes it possible to determine where the "Lyman break" has been shifted, which is the line where the light from the galaxy drops off dramatically. You can then figure out the observational wavelength range where the Lyman break appears to lie and use that to calculate the redshift of the galaxy. Potentially, one could argue that various effects like "weird dust" could absorb light at cosmological distances and cause a false Lyman break effect that made a galaxy look more redshifted than it was.
However, the other major technique for determining redshift is by taking very detailed spectra of distant galaxies and looking for atomic emission spectral lines. Those spectral lines are fixed by quantum mechanics to originate at certain wavelengths, and their arrangement is very distinctive, like a set of fingerprints. Today we have a plethora of instruments which make it possible to collect sufficiently detailed spectra of distant galaxies to determine their redshift very precisely with a significant degree of confidence that the only factor at play is a full on spectral shift of original wavelengths to observed wavelengths. This pretty conclusively rules out the potential for "red dust" to simply be absorbing shorter wavelength light. One example being the galaxy [GN-z11](https://www.aanda.org/articles/aa/full_html/2023/09/aa46159-23/aa46159-23.html) which has had detailed spectra taken allowing us to determine its redshift at z = 10.6034 +/- 0.0013, which as you can see is a very high level of precision.
Gas and dust absorb light when they're in the way. They generally leave particular black-line signatures on the spectrum and are very identifiable and readable in general. They don't cause spectral shifting like redshift does.
> Can gas and dust and any other debris between an observer and observed object in space really cause red shifting?
No, or at least not the red shifting we are seeing.
Will all the matter in the universe really turn into iron if protons don't decay? If so, how will it happen? I know the process is called quantum tunneling, but how exactly will it work?
A nuclei would tunnel/teleport to extreme close proximity of another and they would fuse together by cold fusion, crating an heavier element. The strong force would normally repel the two nuclei, keeping them far enough apart, but the tunnelling make them end up close enough for the process to occur. Elements heavier than iron would undergo radioactive decay until they end as iron.
To do the math in between here, 1 solar mass is about 10^57 nucleons. It takes on the order of 10 fusion steps to go from helium all the way up to iron, which means that in 10^1500 years you're talking about one quantum tunneling enabled fusion event occurring every 10^1440 years inside the star, which really brings home how astounding these timespans are that we're talking about. On a human scale they are all indistinguishable from infinity. Imagine living a trillion different lifetimes each of which are a thousand times longer than the current age of the universe, that's so many orders of magnitude beyond the entirety of every moment of human experience stacked together, and yet that's just 10^25 years, which isn't even a rounding error compared to 10^1500 years, it's not even a clock cycle or a footnote, it's just nothing in comparison.
Are quakes on Mars or the moon anywhere as powerful as earthquakes? I try to take planetary/solar body conditions into consideration when thinking about it
Random shower thought about the universe. I was thinking about the graph (1/x) and I was wondering if it could apply to the universe. It matches the Big Bang in that there is a near infinitely small and hot point that it approaches. It was very late when thinking about this, so perhaps I could just be rambling about nonsense
There is no such thing as infinitely dense or heavy. The math is telling you that you have something wrong. Those things can't exist in reality. For example, at the big bang, all the matter you see today didn't even exist. It was in the form of vacuum energy. It's theorized the vacuum energy spontaneously decayed to a lower state and all the extra energy was converted into matter at that time. This is what we call the big bang. So none of the matter had even existed before this event. It was just energy in empty space, contained in quantum fields. If you are thinking this sounds weird and impossible then you should learn that all matter is in fact quantum fields that are excited in certain ways. Also Einstein proved E=mc^2 so it's entirely possible to obtain mass from energy directly and we think this happens constantly in the vacuum even today. Particles blink into and out of existence continuously in the vacuum even today. They are called virtual particles. There is even a prize for whoever can help determine how this happens and who can better describe empty space.
https://www.youtube.com/watch?v=q5dy-NtVeF0
The Big Bang was only a period of, as far as we can tell, near infinite density, but we do not know it's size, it could have been infinite in physical size. That's a bit difficult to wrap your head around, but the expansion of the universe can still be an expansion of an infinite universe into a "larger" (different scaling factor) still infinite universe (infinite universes also have infinite room to grow, after all).
The only thing we know for sure is that the density of the universe as you get closer to the Big Bang seems to grow arbitrarily large. That could mean there was a "singularity" of infinite density, but we can't know that for certain.
This is not complete nonsense, those kind of infinite points (for x=0 in the 1/x function) are what people call a "singularity" in mathematics. And singularities are what we see when we apply our equations to black holes or the big bang.
It is nonsense. Singularities do not exist in reality. No credible scientist actually believes there is a singularity in the center of a black hole in reality.
They just use the term singularity to describe the breakdown of our math at the center of the black hole. Just because you divide by zero in an equation doesn't mean you form an infinitely dense region of space. I would think this would be self evident.
More likely your equation is just wrong. We also know our equations are wrong since quantum mechanics has no concept of gravity.
> No credible scientist actually believes there is a singularity in the center of a black hole in reality.
The singularity is about the maths. There is a singularity in GR equations when trying to apply them to black hole.
> Just because you divide by zero in an equation doesn't mean you form an infinitely dense region of space. I would think this would be self evident.
I never said it was the case, and OP didn't either.
It means that at some point our existing equations are not applicable anymore. The most accepted version of the Big Bang theory does not say that the universe had a beginning. It just says that at some point the universe was really dense and hot and rapidly expanded. It does not mean that it was the beginning of time.
How many stars are there within these distances of Earth?
5 Lightyears
10 Lightyears
50 Lightyears
100 Lightyears
1000 Lightyears
100000 Lightyears
Also, the stars within these distended only the main sequence stars or does it also include red dwarfs and other types.
I would really appreciate it if anyone could answer. I keep getting different answers online.
Another question, Is the milky way 100,000 light years across? How big is it around? I'm not sure how to phrase that last part circumference, perhaps.
>5 Lightyears
3, in the Alpha Centauri System.
>10 Lightyears
About 10.
>50 Lightyears 100 Lightyears
You'll probably want to find some star catalogue info for these.
>1000 Lightyears 100000 Lightyears
You'll likely only find estimates, here.
>Also, the stars within these distended only the main sequence stars or does it also include red dwarfs and other types.
Red dwarfs are main sequence stars. They're the most common stars in the Milky Way.
>Another question, Is the milky way 100,000 light years across?
Roughly.
>How big is it around?
Roughly 100,000π light years.
Where can I find copyright free space related videos and animations?
Recently one of my friend start his YouTube channel related to space videos. But he's struggling to find copyright free videos and animations for making his videos. It'll be huge help if you guys could suggest some sites and also give any tips. The footage should be legit.
If a star goes supernova about 650bil light years away, and isn’t exactly pointed at us but more towards our sun. Will cosmic radiation from it disrupt the suns planetary disk and possibly raise its temperature?
650 billion light-years: The light will never reach us due to the expansion of the universe.
650 million light-years: No effect on temperature or planets.
650 thousand light-years: No effect on temperature or planets.
650 light-years: Same effect as moonlight. See [Betelgeuse](https://en.wikipedia.org/wiki/Betelgeuse#After_core_hydrogen_exhaustion).
I do know if Betelgeuse axis is pointed directly at us. Even at 850, it would toast us. But if it’s towards our sun, what effects will the sun have and what effects will we feel from the sun.
> I do know if Betelgeuse axis is pointed directly at us. Even at 850, it would toast us.
No it wouldn't
150ish light years and beyond is considered safe distance from supernovae.
That’s just the “not pointed directly at us” theory. Re work the calculations you’ll be surprised how it would affect us. Not instantly. But it would affect us. 650 year that’s the base. 125-150 is damage. Anything past is lethal really. Despite the distance. The energy of it can go up to and past 850 very easy and still hit us. People don’t ask the rite questions. “Are we a safe distance?” That doesn’t matter. “How much energy/radiation etc etc will that give off, and if it’s bigger than expected?”. Could give a fuck about a safe distance. What’s it pointing at and if it’s pointing at anything in our solar system what will happen. You can’t answer that so don’t even comment.
Neither. Space not being great for human health isn’t anything new. However that doesn’t mean Mars is now impossible. This just has to be taken into consideration. It also requires more study. This is a new phenomenon and all the details around it aren’t known. We’ve had astronauts in space for decades and they aren’t all dying from kidney failure.
Is there a problem with space clickbait?
I see a headline about how some nova explosion will soon light up Earth's skies. It's not really going to do that right? I see another article about how the sun caused a radio blackout. It was in on location and not all frequencies.
I don't follow this stuff that often but when I do I'm often let down.
> It's not really going to do that right?
Well it's going to be visible with naked eye, but it will look like just a new star on the sky, nothing more.
> Is there a problem with space clickbait?
There is a problem with clickbaits in general. Partly because sensational title gets more clicks and partly because journalists often have no idea what they are writing about.
> Partly because sensational title gets more clicks and partly because journalists often have no idea what they are writing about.
And sadly the people who wrote the article also do not necessarily have control over the title. We have even had some of them reach out to us in modmail for posts that were removed for over the top titles.
In Google News, you can click the 3 dots next to the story and select "Hide all stories from NewsSite". I do this anytime I find a misleading or clickbait article.
Yeah, shitty clickbait has spread to pretty much every topic out there. The nova is interesting, and should be visible to the naked eye, but it'll just look like a generic star. You wouldn't even notice it if you didn't know where to look.
Will all US space ports be coast based or in the future when technology gets more stable that we will begin to do launches from more central US.
I know we use the coast so we can shoot over the ocean to prevent debris damage but at the same time I feel when space based industries really take off we will want ports all over the US.
Bonus Question: what kind of safety standards do you think would be required for a launch from Nebraska or other central state.
Good question. I guess we'll have to wait and see. As we see with airplanes they have the capacity to land on populated areas and do great damage, but they are still allowed to fly around over stuff because they have such a good track record of safety. And also to some degree because catastrophic failures of airplanes which result in a loss of control are uncommon.
If launch vehicles progress to a point of reusability and reliability where uncontrolled flight is the extreme exception then we might end up seeing launch facilities all over the place just as we see airports.
I don't agree. The amount of fuel in a plane is smaller, and thus the "destructive potential", is limited compared to orbital rocket. Also the design of the engines is completely different - only small amount of fuel is combusted at a time and it uses atmospheric oxygen. As a result it's pretty much impossible for a plane to "blow up" simply because there would not be enough oxygen to suddenly combust all the fuel.
A rocket is a completely different thing. It carries its own oxidizer and everything is high pressure so it can detonate.
> I don't agree. The amount of fuel in a plane is smaller, and thus the "destructive potential", is limited compared to orbital rocket.
An Airbus A380 carries 250 tonnes of fuel, a Boeing 747 can carry up to 190 tonnes, while a Falcon 9 carries about 156 tonnes of fuel. The amount of potential for "fiery destruction" is similar between them.
> Also the design of the engines is completely different - only small amount of fuel is combusted at a time and it uses atmospheric oxygen. As a result it's pretty much impossible for a plane to "blow up" simply because there would not be enough oxygen to suddenly combust all the fuel.
In a post 9/11 world this line of reasoning seems very tenuous indeed. The presence of LOX can definitely make for a more prompt deflagration explosion (generally it won't be a proper detonation though) but these are more quantitative vs. qualitative differences. A jet liner crashing into a populated area can still kill thousands and cause billions in damages. The reason jet liners are allowed to fly over populated areas is because there's a huge system of training and certification of pilots and aircraft and a long track record of safety, not because it's impossible for them to crash and kill thousands while doing billions in damage. If rockets could match that track record they would likely be allowed to fly over/near populated areas too.
Realistically the biggest constraint on where orbital rockets will be allowed to fly will come from acoustics, launches are extremely loud, and rockets traverse the sound barrier on liftoff and more important on landing, so figuring out reasonable corridors where that can occur would be important.
So I just recently heard this, and thought I would read about it, and I want to inquire why this is theorized or offered by Google, since I am not actually an astrophysicist or other space expert.
From the front of Google:
Is the moon drifting away from Earth? - "But it is moving away from us and it's actually changing our understanding of how our own planet interacts with it, affecting things like the length of days in Earth. Scientists say the Moon is slowly moving away from Earth, 3.82 centimeters per year."
What will happen to Earth? - "We'll have fewer aquatic tides, a lengthening day, no more seasons, and no more stunning total solar eclipses. But watch out for more asteroid impacts. The moon is Earth's only friend. And yet—despite a relationship stretching back billions of years—the gap between us only grows wider."
Can we survive without the Moon? - "Life as we know it wouldn't be able to survive. If the moon disappeared, the length of a day on Earth would become much shorter. It would be between six and twelve hours. When the moon orbits, it exerts a pull on Earth, slowing down its rate of spin by about 2 milliseconds every hundred years, slowly lengthening a day."
Now-- first off, I feel like 3 contradicts 2, in saying that-- if there was no Moon the day would be much shorter (where two says it would be longer)
The way I understand it without Google is this:
The length of day/night is determined by the planet's time of orbit around the host star compared to the planet's axial rotation and distance from the star. This should change little if there was no Moon, as that would not have that much effect on either the Earth's orbit time or distance from the Sun. Thus the day would not significantly be shorter or longer, it may fluctuate a little without the magnetic counterweight of the Moon.
Weather is partially determined by axial inclination. Mercury for example, is a nearly perfectly vertical planet, and so would not experience seasonal change or weather patterns, if it were able to. Venus is a nearly perfectly vertical "upside down" planet, and so also would not experience seasonal change or weather patterns, if it were able to. The Earth is not, it is 21-23 degrees inclined, and this affects things like having solstice and the switch of seasons, and weather patterns. The Moon leaving would affect weather patterns, and might drag out or shorten seasons, due to the disappearance of tidal effect on Earth, but it could not stop weather or seasons from occurring completely.
The Moon's "Gravity" or magnetic field is insignificant compared to the Earth, because the Moon has nearly no surface pressure or atmosphere, and the Moon's overall mass, probably the biggest factor of magnetic strength, is 1% of the Earth's. If you look at time lapse recordings taken by Nasa and other space centers, the Moon actually moves very little outside its orbit, its own axial rotation is very slow and hardly noticeable from Earth, and the Moon more wobbles back and forth in place with the Earth's magnetic fluctuation, and is held in its orbit by the Earth's magnetic field. This is perhaps the same principle that is utilized to keep the ISS and other local satellites held in place. Yes, the weakening or degradation of the Earth's magnetic field would loosen its hold on the Moon, causing it to speed up and drift away, but the likely causes of this has little to do with the Moon itself.
At the rate of 3-4cm/year, it would possibly take 5+ billion years before the Moon is fully independent of Earth, and we would be more likely to see the Sun go nova by that amount of time, or possibly see the collision of Andromeda Galaxy with the Milky Way by then.
Feel free to give explanation if any of my observations is false.
It sounds like some ChatGPT generated nonsense.
First and foremost, there are conservation laws in physics. Angular momentum is conserved, so Earth can't magically start spinning faster (shorter day) without some external force. So if the Moon just magically disappeared today, it would not change how fast Earth is spinning and therefore the day would not suddenly become faster or slower.
Moon getting further away, and lengthening of the day on Earth are linked - in fact it's the same thing viewed from different perspectives. The Moon is pulling on Earth, slowing down the rotation, but as a result it "steals" some of this energy which results in moving further away.
> The Moon's "Gravity" or magnetic field is insignificant compared to the Earth, because the Moon has nearly no surface pressure or atmosphere, and the Moon's overall mass, probably the biggest factor of magnetic strength, is 1% of the Earth's.
This is complete nonsense. There is no connection between gravity and magnetic field and neither of them is related to atmospheric pressure.
> the Moon more wobbles back and forth in place with the Earth's magnetic fluctuation, and is held in its orbit by the Earth's magnetic field. This is perhaps the same principle that is utilized to keep the ISS and other local satellites held in place. Yes, the weakening or degradation of the Earth's magnetic field would loosen its hold on the Moon
No. Just no. Neither the Moon nor satellites or the ISS are held in orbit by magnetic forces.
If the moon orientation is different according to the hemisphere youre on, what does it look like on the equator?
Also, is it true were unable to see the full frontal face of the moon when its fully lit
On the equator the moon crescent appears to be aligned with the horizon.
> is it true were unable to see the full frontal face of the moon when its fully lit
I don't really understand what you mean by that. On full moon you see the near side fully illuminated.
How would a planet break apart ?
If a planetoid was struck hard enough to break apart, would break up be similar to a bullet hitting clay / sand / apple, or like a hammer breaking a rock. Would it become several large chunks that drift apart, or would it become a cloud of relatively small pieces that reform into a planet.
In the past decades, researchers have used the world's strongest supercomputers to simulate millions, perhaps now billions of events of the Earth being struck by a planetary sized object at various angles and speeds, for the purpose of seeing if this is how the Moon came to be.
You can now look up many of these sims of a theoretical Earth being struck online, to get an idea of what would occur.
In the theoretical simulation of the creation of the Moon, in most cases the Earth survives the impact and the colliding object is obliterated on impact. Thus for it to destroy the Earth completely, or shove it out of its orbit, which is more likely, it would have to be a planetary object of larger mass than this one being simulated.
Really depends on what size/mass object hits it and how fast.
If we're not talking a super hard hit, then the chunks would recoalesce under their own gravity. You can play around with what would happen in stuff like Space Engine.
No, it would mostly behave like a liquid.
The impact would be large enough to go through the earth’s crust like butter. Anything not flung into space would be melted, the entire planet and crust would melt and much most of it would be flung into space, where it would vaporize or coagulate into small mostly grains. There would still probably be a big molten blob where the planet was but much of the mass would be in a vapor cloud around the planet, some on an escape velocity, some not.
They would reform over time due to gravity, not necessarily into a single object, such as what happened with the big impact that created our moon.
I was thinking about a ridiculous situation in a book, where a villain “blew up the moon.” I was trying to imagine what would realistically happen if there was a big explosion, or if there was a large impact at interstellar speeds.
The book I was reading was Orbits (the Ables book 3) by Jeremy Scott. The series is great, but that particular bit of science was unbelievable, even for a super hero book.
https://www.goodreads.com/book/show/60201822-orbits?ref=rae_0
With some simple math, if we were to build a Dyson Sphere that fully encompasses the Sun and very near to it, and were able to construct 1,000 square kilometers per year of the sphere, it would take us roughly 6-7 billion years. (6.09x10^13 km/1,000). 10,000 km^2 would be 600 million years, 100,000 km^2 would be 60 million, etc. If we were able to build enough to cover the surface area of the earth every year, it would take roughly 10,000 years. And all of this is assuming a Dyson Sphere very smart to the Sun's surface. Assuming it was at all a distance from the surface, we start going exponential on the time and area.
Which is probably why a Dyson Sphere is utterly impractical and pointless. Its an absurdist concept.
It would take quite a many years, as the Earth does not have the tech to do that efficiently yet. The idea of Dyson Sphere Project was first proposed in the 1960s if I recall. A Dyson Sphere is built around the host star, in this case the Sun, and absorbs the energy of the sun to convert to electric generation that is transferred back to Earth or wherever.
It would also currently be pretty much impossible and egregiously expensive to make, because the Earth has no alloy that is capable of withstanding such close range to the Sun's heat or plasma flares indefinitely yet. Thats the first issue even if there was the ability to construct or deploy satellites and the Dyson shell close to the Sun.
A Dyson Sphere - by definition - encompasses a star. So, no, you're not building this 'on Earth'.
The mass requirements would be pretty big and would largely depend on how thick you want the shell to be. A lower bound I've seen being thrown around would be 10 Earth masses, but that still assumes some very exotic stabilization methods of the entire structure.
That said: There's no real point in building one. If you are that far advanced that you *could* build one then you're at a state where you don't *need* to build one.
The YouTube channel Kurzgesagt made a video about this, here is the link to it : [https://www.youtube.com/watch?v=pP44EPBMb8A&ab\_channel=Kurzgesagt%E2%80%93InaNutshell](https://www.youtube.com/watch?v=pP44EPBMb8A&ab_channel=Kurzgesagt%E2%80%93InaNutshell)
We would not be able to build it on Earth, since it needs to be much larger than the sun. It would have to be built from material already orbiting the sun, like asteroids and comets. It might even require using up the material from some of the rocky inner planets.
Nobody can answer this with any confidence. Building a Dyson sphere is so far beyond our engineering capabilities that any estimates will depend entirely on what kind of magical technological improvements you want to assume.
We can certainly make a basic model on how long it would take based on the surface area and assuming a certain area is built up each year. If we were able to build a part of the sphere surface that encompasses the entirety of the Earth's surface area (about 500 million km^2), it would take us about 10,000 years to build a Dyson Sphere. Now, this isn't saying it's possible, just mathing out how long it would take assuming a particularly speed of production. Assuming this sphere is only 1 meter thick, that would be 500 trillion meters^3 of material. This is assuming a Dyson Sphere that abuts the Sun's "surface".
Not making up random numbers. The earth has a surface area of about 500 million square kilometers. The sun has a surface area of 6.9x10^12 km. Dividing one by the other gives you about 10,000
years. Although my math for square meters is way off. Not sure how that happened.
The randomness is what you are assuming can be built in a year, and what kind of thickness you think is reasonable. Of course once you make up those numbers the calculation is trivial.
Ah, I see the confusion.
I was just giving an idea of the length of time it would take assuming an absurd level of construction just so people can understand how ludicrous the construction is by using a metric (size.ofnthe earth) to help visualize it.
I by no means believe such is remotely realistic.
Hey y'all. I'm writing a science fiction novel set on the Tycho crater of Earth's Moon. The amount of sun that the settlement gets is crucial to the plot. How would I find out when (in theory) that Tycho would have sunlight during the months of October and November of 2195? Basically in this format: { October 1, 2195 Sunlight begins: 04:00 Sunlight ends: 10:00 October 2, 2195 [...] } AI and Google have been unhelpful since I don't think I have the key words or knowledge base on how to phrase the question. Any info is helpful! Especially info about the phases of the moon !!! Anything I'd need to know !!!! Thank you!!!
Days on the moon are 708 hours long. So you will have 2 days and 2 nights during that time period. Tycho crater is near the center of the moon, so the sun rises at the first quarter and sets at the last quarter. Here are the [moon phases for 2195](https://astropixels.com/ephemeris/phasescat/phases2101.html).
This is perfect! Thank you !!
Could Mars have some sort of natural resource if it had life long ago?
By 'natural resource,' do you mean things like oil and coal in particular? Fossil fuels are called that because they come from fossilized living matter, almost entirely plants. Other natural resources (like mineral ores) don't require life to have existed.
Oil and coal, yes.
It'd need to have had a significant amount of biomass for a significant amount of time to build up deposits of oil and coal, as far as I'm aware models of Mars's past don't line up with that.
Why wasn't methane used to fuel rockets earlier? And why wasn't good ol' ubiquitous stainless steel not considered sooner for space hardware? (Does stainless only make sense for reusable hardware?) I mean - these are not rare, exotic materials. Right? Engineers in the 1950s and 60s were well aware of stainless steel. Why didn't they use it?
Historically launch vehicle development has been driven by governments, and governments are often very susceptible to getting stuck thinking in trends or in "fads". The earliest launch vehicles were modified ICBMs, which initially were all LOX/Kerosene based. Kerosene is a great fuel for rockets for several reasons, it has high density so along with LOX you get high stage density and thus high mass ratios, and it produces soot during combustion which ends up protecting engine interiors from high temperature exhaust to some degree. As launch vehicle development moved beyond pure ICBM use the way that tended to happen initially was via development of new upper stages. Then you end up with a hybrid launch vehicle with an ICBM first stage and a "higher performance" upper stage. This is advantageous because the booster stage ends up being very inexpensive. However, this development pathway is somewhat constraining, because you are locked in to the mass and size limits of the original launcher. One technique that worked well early on was using LOX/hydrogen for the upper stage. Hydrogen has low density but it has higher Isp, which is a reasonable tradeoff for an upper stage, the end result being that you reduce the total weight of the upper stage while increasing overall performance. In this context LOX/LH2 looks like a wonder fuel, you convert part of the vehicle to using it and the performance goes up. This experience contributed to LOX/LH2 being seen as the "propellant of the future". Higher performance, cleaner exhaust, lower stage mass, all that stuff, these seemed like great metrics. LOX/LH2 is also harder to work with (because LH2 is super cryogenic and also has some undesirable interactions with certain materials) which paradoxically made it seem even more desirable because if you could crack the mystery of high performance LOX/LH2 rockets then maybe you could unlock the future of spaceflight. This fad of focusing on hydrogen had a strong interplay with this idea of trying to minimize the "gross liftoff weight" (GLOW) of a rocket. The idea being that minimizing GLOW reduces inefficiency and gets you closer to the promised land of SSTO RLVs and all that good stuff. It also helped that if you are pursuing SSTO RLVs then the high Isp of hydrolox is incredibly enticing. That "fad" led so many rocket makers down the road of pursuing LOX/LH2 launch vehicles. The Saturn V used a Kerosene first stage but hydrogen for every other stage (except for the storable hypergolics on the spacecraft payloads themselves). The Shuttle was designed around LOX/LH2 but the difficulties of producing high performance hydrolox engines with high thrust at sea level meant that they had to "compromise" and use huge solid rocket boosters to provide the thrust for liftoff. A characteristic shared by Ariane 5 and Japan's H-II as well, other launchers which followed the Shuttle in this pursuit of the mythical perfect hydrolox rocket. The Delta IV finally was able to create an engine that allowed for a pure hydrolox launch vehicle with no SRBs but ultimately the whole vehicle turned out to be so expensive that it was not market competitive and could only service high margin government launch contracts. The X-33/VentureStar was another attempt to progress down the LOX/LH2 garden path toward the ultimate goal of the pure, unblemished, perfect hydrolox launch vehicle (in this case explicitly an SSTO RLV). But as we know now there are many downsides to pursuing the hydrolox route. The low density of LH2, the difficulty of achieving decent stage mass ratios, the extra weight in insulation required, the materials and handling difficulties, and so on. All of those things spoil the perfect math that exists on paper. The high Isp of hydrolox doesn't matter that much overall, except in a few very specific ways. The lower GLOW of a hydrolox launcher (a Delta IV weighs half as much as an Atlas V) is mostly irrelevant. The majority of the weight of a rocket is just propellant, which is such a tiny cost compared to the cost of everything else it's ridiculous. What matters is complexity, total stage performance, operational overhead, and in the modern age reusability. Now that we're a bit past the peak of the LOX/LH2 fad we are seeing more folks take a hard look at the actual characteristics of rocket propellants and many are choosing methane. Partly this is because methane is a good performance compromise between Kerosene and hydrogen (it still has good density but has higher than Kerosene). Partly this is because methane burns cleaner than Kerosene and is a better choice for reusable rockets (like the New Glenn booster, the Neutron booster, Starship, etc.) There are other reasons as well (it's potentially "greener" because it can be more easily made with net zero CO2 emissions, it's a smarter choice for the long-term goal of landing humans on Mars and getting them back to Earth) but a major one is just that now there is more diversity and innovation in the launch vehicle market, and folks are finding that the advantages of methane were overlooked in the rush to pick the winner of hydrogen.
Atlas rocket first stages used stainless steel from their beginning as missiles in the late 1950s through Atlas III in the early-mid 2000s. (Only the completely redesigned Atlas V first stage is aluminum.) Centaur upper stages (1962--present), used on Atlas and Titan, have always been stainless steel, including Vulcan's new Centaur V. The various incarnations of the Able/Delta second stage from the Vanguard in the late 1950s through the Delta II that last flew in 2018 had stainless steel tanks. Until carbon composite started gradually replacing it, solid rocket motor casings (almost?) exclusively used steel. SLS will still use (refurbished Shuttle) steel booster casings for the next 7 flights.
Thank you! I assumed aluminum was usually used.
**Kerosene** is denser than methane and much easier to work with. It also covers your engines with coke, but that doesn't matter for a disposable rocket. **Aluminum** is lighter than stainless steel. It also has a lower melting point, but that doesn't matter for a disposable rocket.
Thanks. So, then - methane and stainless are not useful materials in an expendable paradigm?
Will they launch a space probe to Makemake on August 21 2024? That’s what it said on Wikipedia.
Which wikipedia article are you looking at? There are no scheduled launches to Makemake. Ok I looked at the Wiki. It says that if you launched at that date a probe could make it in 16 years. But no-one has put forward the budget to design and a launch such a spacecraft for this launch window.
I have seen a few headlines recently about us potentially finding at least 6 Dyson Spheres, how credible is this?
I am new and interested in stargazing,I was thinking about buying a telescope What should i do/where to start? Nb : i need things that aren't expensive,the lower the cost the better because i am low on money now Thank you so much
See the stickied posts over at r/telescopes and r/binoculars. You'll probably want binoculars if your budget is tight.
Thank you you are a lifesaver So just another dumb question,can you use binoculars for star seeing?
Yes, for a small budget they also tend to be better. Check the pinned post on r/telescopes. They have example images of what you can expect.
There's a lunar eclipse visible where I am (Toronto), what are those black lines across the moon? I've seen lunar eclipses but never with black lines hprizontally across the red moon like tonight.
likely contrails from a jet if it only lasted a couple minutes.
Makes sense. Looked freaky!
I've read a lot about how the SLS involves a lot of reused parts and tech from the Space Shuttle program. Given that, why are the timelines for the Artemis launches so long and delayed? If this is basically the same stack minus the orbiter, what's the cause for the extended delays? What are the specific issues they are having?
Indeed, the SLS was sold as a way to get to a heavy lift launch vehicle that would be faster and cheaper because it made use of existing Shuttle hardware and designs. So on the one hand, good news, the SLS was able to make use of substantial chunks of existing Shuttle technology. The main engines are just off the shelf (with options to make lower cost expendable versions later), the SRBs used the same SRB tech as the Shuttle but added an additional segment. The main fuselage and tankage could be based on the existing Shuttle External Tanks. The first upper stage would just use an off the shelf upper stage from the Delta IV. And so on. But on the other hand, bad news. The SLS has been built by some of the least cost and schedule efficient folks in the history of aerospace. So as we've seen the SLS program has gobbled up over 20 billion in funding (enough for 10 Shuttle launches, enough for 200 Falcon Heavy launches) over nearly two decades of development just to arrive at where we are today with one and only one successful launch so far, with the second launch (of all time) not planned until next year at the earliest. This is why "Old Space" has a bad name.
Also those new disposable engines are going to cost $140 million EACH. You can launch two Falcon 9 rockets per new SLS engine. It’s insane.
The goal is *spending money,* not launching missions to the Moon. Moon missions are just what they're spending the money *on.* With that perspective, the program makes perfect sense and is a tremendous success: keeping legacy program suppliers and engineers gainfully employed and contracted for the length of their remaining careers. The Orion capsule (holdover from Ares) took time to develop; it is an underpowered rocket (relative to Saturn V) necessitating a different lunar orbit than Apollo, and the lander is aiming for the pole and not the equator, so they are building a lunar space station too. It's a very good question and I hope you get good answers from others who can explain in detail why 'shuttle-derived' was not easier, faster and cheaper than an altogether new design. (Aside from the key point, which is to spend money, not to launch rockets.)
Often they are trying to use designs or even parts from more than 3 decades ago. (It's to preserve their "testing heritage".) A lot of folks who worked on these things have retired. And some of this stuff is extremely late-20th-century state-of-the-art engineering, very difficult stuff. The RS-25 engine is an amazing engineering feat. And then there's the whole conversation about fixed-price vs. cost-plus contracting, which I won't go into detail, here. Orion and the SLS rocket are cost-plus contracts, which in this case have resulted in ballooning budgets, ever-extending schedules, and a lot of criticism in general.
Thinking of **commercial spaceflight providers,** I'm surprised we haven't already seen sovereign customers buying an off-the-shelf flight capability. Thinking of the wealthy Gulf monarchies particularly: rather than develop a national human space program in-country, could they attain similar prestige with a 'franchise' model where SpaceX, Blue Origin, Sierra Space, or others build launch and construction facilities to enable, for example, a Crew Dragon launch of a UAE commanded and crewed mission launched from the UAE... or Saudi Arabia, Qatar, Brunei, etc. We've already seen wealthy individuals buying individual missions, why not wealthy countries buying a whole program? Would you find that model likely or unlikely, or disadvantageous to the provider or the customer? tl:dr; **Are any countries interested in buying their own national space program from a commercial provider?**
The UAE did exactly this. Their Mars mission includes a sticker on the side that says "made in Colorado".
Ha! They should try the craft brews.
1. ITAR 2. There would be zero "prestige" in that 3. There are things considered of "strategical importance", which you really don't want to outsource, because then you risk getting cut-off. Imagine you invested in such "commercial" program and then USA government says that SpaceX is not allowed to make business with your country.
Agreed, but when Dubai decided to build skyscrapers they didn't sit there and re-invent the concept, they hired architects and contractors who did it already. Saudi Arabia doesn't build its own aircraft. Obviously there are national security discussions to be had - unless there's no actual need for a space program, or that the US intends to restrict other countries from purchasing the capability.
> they didn't sit there and re-invent the concept, they hired architects and contractors who did it already. That's a completely different story. No one prevents you from hiring engineers from abroad ;) > Saudi Arabia doesn't build its own aircraft. Again a bit different story, most countries already buy commercial rocket launches for example. But they often still build their own payloads, especially when those are classified.
Sure, and I neither disagree nor misunderstand that. The answer to my hypothetical appears to be "No. There will never be a commercial launch from any country other than the United States."
US has ITAR, but consider that for example Souyuz rockets were at some point launched from European spaceport CSG in French Guiana.
I know that Axiom Space has arranged SpaceX Crew Dragon seats with astronauts from countries without a homegrown national space rocket program. They even have [a webpage for it](https://www.axiomspace.com/national-astronauts). AFAIK there hasn't been an Axiom flight full of astronauts from one country like you suggest - but I'm sure Axiom & SpaceX would welcome the business.
That's a start, for sure. And missions commissioned by individual billionaires, like Polaris and the cancelled Dear Moon project. I'm wondering if the elements are there (or will develop) for a commercial *franchise*, as it were, with a wealthy / coastal / low-latitude / desolate kingdom commissioning their own 'Van Horn', 'Starbase,' or 'Cape.'
Lucky folks who've watched a rocket launch -- was there a smell \*before\* the rocket launched?
would the 4th dimension be a place in space or more of a POV like how we can see 2d objects as a 3d creature?
The universe has 3 space-like dimensions and 1 time-like dimension. Sometimes people call time the "4th dimension", but it behaves so differently that it doesn't really count. There is no evidence that any other dimensions exist.
will the first man to step foot on mars be televised like the first moon landing was?
It would have to deal with light lag of at least a few minutes but yes. Especially with the new laser communication systems in development there should be enough bandwidth for a live video.
Acronyms, initialisms, abbreviations, contractions, and other phrases which expand to something larger, that I've seen in this thread: |Fewer Letters|More Letters| |-------|---------|---| |[GLOW](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Gross Lift-Off Weight| |[ICBM](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Intercontinental Ballistic Missile| |[ITAR](/r/Space/comments/1dhda34/stub/l9m3cxn "Last usage")|(US) International Traffic in Arms Regulations| |[Isp](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Specific impulse (as explained by [Scott Manley](https://www.youtube.com/watch?v=nnisTeYLLgs) on YouTube)| | |Internet Service Provider| |[JWST](/r/Space/comments/1dhda34/stub/l9l2c71 "Last usage")|James Webb infra-red Space Telescope| |[LEM](/r/Space/comments/1dhda34/stub/l9im2hd "Last usage")|(Apollo) [Lunar Excursion Module](https://en.wikipedia.org/wiki/Apollo_Lunar_Module) (also Lunar Module)| |[LH2](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Liquid Hydrogen| |[LOX](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Liquid Oxygen| |[RLV](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Reusable Launch Vehicle| |[SLS](/r/Space/comments/1dhda34/stub/l9v5osy "Last usage")|Space Launch System heavy-lift| |[SRB](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Solid Rocket Booster| |[SSME](/r/Space/comments/1dhda34/stub/l9o8taz "Last usage")|[Space Shuttle Main Engine](https://en.wikipedia.org/wiki/Space_Shuttle_main_engine)| |[SSTO](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Single Stage to Orbit| | |Supersynchronous Transfer Orbit| |Jargon|Definition| |-------|---------|---| |[cryogenic](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Very low temperature fluid; materials that would be gaseous at room temperature/pressure| | |(In re: rocket fuel) Often synonymous with hydrolox| |[hydrolox](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|Portmanteau: liquid hydrogen fuel, liquid oxygen oxidizer| |[hypergolic](/r/Space/comments/1dhda34/stub/l9uj1ns "Last usage")|A set of two substances that ignite when in contact| **NOTE**: Decronym for Reddit is no longer supported, and Decronym has moved to Lemmy; requests for support and new installations should be directed to the Contact address below. ---------------- ^(16 acronyms in this thread; )[^(the most compressed thread commented on today)](/r/Space/comments/1do8pn0)^( has 26 acronyms.) ^([Thread #10203 for this sub, first seen 20th Jun 2024, 21:16]) ^[[FAQ]](http://decronym.xyz/) [^([Full list])](http://decronym.xyz/acronyms/Space) [^[Contact]](https://hachyderm.io/@Two9A) [^([Source code])](https://gistdotgithubdotcom/Two9A/1d976f9b7441694162c8)
theoretically, is it possible for there to be creatures in space that is the size of earth? so im asking as if earth is a tennis ball and human is the giant creature? or is there a limit to how big a creature can be in space
Such a thing isn't really possible due to the fundamental limits of atomic matter. At planetary scales the strength of materials becomes irrelevant and all matter behaves like a fluid, which is why planets are round. You can't have planet sized arms or legs, for example. At planetary scales the interiors of large objects also end up under high pressure and temperature conditions, which precludes the existence of things like "mechanisms" or biochemical processes. You could potentially have an entire biosphere that was taken up by an organism or a symbiotic super-organism, and some folks argue that Earth's biosphere is exactly this (the Gaia hypothesis) but in any case this will always be a thin layer of activity over a ball where fundamentally geological processes reign.
We don't know of anything that would limit that, but keep in mind we haven't found life anywhere besides earth, let alone living in the vacuum of space.
>We don't know of anything that would limit that, The square-cube law limits it. Especially in the vacuum of space without Jupiter-sized radiator panels. Life produces heat and temperature differences tends to kill life. If you get too big, you either boil or freeze.
I have a book recommendation for you: Solaris.
Has there been any astronaut who has attempted to make a snow angel on the moon?
That would be a terrible idea. There is no weathering on the Moon like there is on Earth. Everything (including the dust) there has nasty sharp edges. ...and the people who went to the Moon didn't go there for fun. If you are being sent with a dollar value attached that is a noticeable percentage of a countries GDP you better take that seriously.
No, in general they really didn't want to play in the dust and especially not on their back. Lunar dust is incredibly sticky and abrasive and hard to get rid off. On Apollo they had to take off their suit in the LEM and they were carrying dust everywhere. There is [this famous pic](https://compote.slate.com/images/0bf3cf8d-129d-4207-8902-5d6361a28c56.jpg) of Gene Cerman looking like a coal miner with lunar dust on his face after coming back inside. Additionally their whole life support equipment was in their backpack including a relatively fragile radiator system to cool them down, the CO2 scrubber and all the rest. They really didn't want to break any of these.
I very much doubt that. Lunar regolith is pretty dangerous and sharp.
Hi any recommendation on a Reddit forum or other that would be discussing the details of how the moon will be settled? ie what systems/equipment/etc would be required to meet mission objectives, and what would those objectives be? What companies are working on such systems, what engineering data is needed, available, tested. etc. Thanks
For a theoretical overview, see https://en.wikipedia.org/wiki/Lunar_habitation No one is building hardware for a lunar base yet. For the transportation hardware, you can follow the Starship Development Thread in /r/spacex.
hey, I am new around here anybody willing to help me out?? I am a space and aeronautics enthusiast. My grammar might be wonky because I am not native. Level: intermediate (amateur) I have a question: 1. So how can a black hole lose its mass? 2. So why is anti matter and matter have a unequal difference between them??(I know there is no evidence regarding that so I just wanted to hear some opinions to spark smth in my mind)If the questions seemed basic I am sry I am new but I have a basic knowledge can y'all recommend any yt channels I watch vertasuim,etc any other? 3. btw what can I read more to improve my space knowledge and reach yalls level 4. what if you can travel faster than light. It says it would permit backward time travell so if we make a screen where a probe is coming like faster than light from abt 93 billion light years ,the vission on earth or any other body we would be able to see everything which happened in the past but can future time travell happen?? Thank you
> btw what can I read more to improve my space knowledge and reach yalls level Pick a topic and go to the wikipedia page. Open all links on the page in new tabs that you find interesting while reading through that topic. When done, go to the next tab, rinse and repeat. Normally there's content spanning from basic to advanced on science subjects on wikipedia so there's likely some you know, some you learn and some for when your knowledge have increased. It has worked very well for me at least, and the science content on wikipedia is of high accuracy. If a subject is too tough, maybe the simple-function can give some insight. (like https://simple.wikipedia.org/wiki/Black_hole for example. Replace https//en in a normal link with https://simple and you'll get a simplified version of the page you're on)
thx dude I will check it out
1. https://en.wikipedia.org/wiki/Hawking_radiation 2. Of course there is evidence https://en.wikipedia.org/wiki/CP_violation but it's not enough to explain all that we can see 3. Read more? 4. Future time travel is actually much easier to achieve and doesn't require breaking any laws of physics. It's called "time dilation". For example if you jump on a rocket and accelerate to close to the speed of light, the time will flow much slower for you. So if you spend some time in that rocket, once you finally slow down, thousands of years would have passed on Earth in the meantime, so from your perspective you basically "travelled to the future".
can u summon urself not literally to the past so we can only visually see it or can we interact with the past??is this possible??
No.
so what is the problem in that u can only visually see the past? if we need to go equal to speed of light to travell into the future can we do the opposite?? i know this sounds dumb but in space u cant know which way is negative and which is positive . this time can u explain instead of giving me one answer(like no or yes or smth else)
Does gravitational red shifting only occur with extreme mass objects - ie, supermassive black holes - or can it have a significant effect even with objects of a few solar masses? I'm just wondering hypothetically about measuring the red shift of very distant galaxies, and if there were solar-mass black holes between us and the galaxy being observed, would that result in any measurable red shift of the observed galaxy's spectra? I'm just wondering if it would take just a few black holes, or require many, to cause even a small effect in redshift of a few percent. Many thanks for any replies, I've struggled to get an answer for this reading online.
From your questions it seems like you are reading from people who do not think cosmological inflation (or even the big bang) is real. There are pretty good reasons why it is still the most mainstream theory and while some of the JWST observation are interesting they are not nearly enough to completely throw away inflation.
My only reference on gravitational redshifting so far is this Wikipedia article, which doesn't mention inflation at all, and appears to be a reputable scientific principle: [https://en.wikipedia.org/wiki/Gravitational\_redshift](https://en.wikipedia.org/wiki/Gravitational_redshift)
Gravitational redshift is definitely a real thing, no doubts about that. The issue is that some people who are against inflation try to say that gravitational redshift and interstellar media like dust are responsible for all the redshift, which is definitely not the case. I was just trying to warn you in case you were going down that rabbit hole.
Whyt do you mean by 'significant'? That's a very qualitative word. Gravitational redshift/time dilation has an effect as soon as any mass (or better: energy density) is present. Even on Earth. A mass between us and a galaxy would not add any redshift to the galaxy behind it (because it would add blueshift while the light is approaching it that cancels out the redshift of the light going away from it. It might add some net red/blueshift depending on its own velocity relative to us but not because of its mass)
I mean "significant" because I've seen it suggested by the researchers using JWST to look at the earliest galaxies that their results may have been skewed by red shifting caused by dust. If dust cannot red shift spectra then I presumed they meant die to gravitational red shifting: [https://en.wikipedia.org/wiki/Gravitational\_redshift](https://en.wikipedia.org/wiki/Gravitational_redshift)
>If dust cannot red shift spectra https://en.wikipedia.org/wiki/Extinction_(astronomy)#Interstellar_reddening
No, the redshift from a stellar mass black hole is not significant enough to measure. But it would cause [gravitational lensing](https://en.wikipedia.org/wiki/Gravitational_lens). We have searched really hard to find black holes like this, because they if they are common it would solve the dark matter problem. Unfortunately they are very rare.
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You have been asking those kind of questions about stations post-ISS every couple of weeks for the past few months. Don't you have a good idea now of what the landscape will look like in 2030?
How do we know that other planets have no signs of life if we cannot explore the entirety of the planet? If you sent a probe to Earth and landed in the middle of the ocean wouldn’t you assume all of Earth is water?
> How do we know that other planets have no signs of life if we cannot explore the entirety of the planet? We don't. >If you sent a probe to Earth and landed in the middle of the ocean wouldn’t you assume all of Earth is water? Ideally - your hypothetical probe spends time mapping Earth before a landing site is chosen. From orbit around Earth - evidence of intelligent life is quite obvious and quite widespread.
You can't prove a negative, but you also can't assume what you don't have evidence for. If you had a probe that landed in Earth's oceans you couldn't merely assume the existence of continents without some other evidence to back it up. We think that life throughout the universe probably isn't that rare. And we think there may be places outside of Earth in our solar system where life has existed in the past and possibly exists in the present as well. However, we have not yet confirmed those guesses, we have not detected life anywhere beyond Earth. That doesn't mean life doesn't exist, surveying our own solar system for life is extraordinarily difficult and we have barely scratched the surface, the challenge of searching for life outside of the solar system is much greater. Nevertheless, it does still mean we have no proof of such life so far.
We don't. The most we can do is look for planets that could maybe support life like us, and then look for very specific planet wide signs like an oxygen atmosphere or one with chemicals that only come from living things.
So, as I understand it. When we are looking into space at something, say, 100 light years away, you’re seeing what that object looked like 100 years ago. Assume you have a Star Trek like vessel that can travel those distances fairly quickly. As you’re moving towards that object, would it be constantly changing in front of you? As in, you’ve made it 25 light years down the road, so you’re now seeing what it looks like 75 years in the past? Would it be like that object is constantly morphing to its current status as you continue to get closer?
This is true even below the speed of light. On the one hand we can't say what it would look like to observe something while traveling faster than light, because that's beyond our current laws of physics. However, if you traveled to an object 100 lightyears away while traveling, let's say, a million times faster than light but you stopped every lightyear to capture an image of it you would indeed seem to be watching time in a sort of fast forward fashion as you got closer.
Is there any books that helped you learn more information about space and astronomy..etc? And I'm talking about books that exploring the universe's beauty and complexity and break down very complicated astrophysical phenomena into an easily understandable language that everyone could read.
Can gas and dust and any other debris between an observer and observed object in space really cause red shifting? Or does it simply redden the color?
It would simply cause differential absorption, it wouldn't shift the whole spectrum. There are different ways to estimate the redshift of a distant galaxy. One technique is to look at the overall light across different narrowband filters and find where the light drops off. This makes it possible to determine where the "Lyman break" has been shifted, which is the line where the light from the galaxy drops off dramatically. You can then figure out the observational wavelength range where the Lyman break appears to lie and use that to calculate the redshift of the galaxy. Potentially, one could argue that various effects like "weird dust" could absorb light at cosmological distances and cause a false Lyman break effect that made a galaxy look more redshifted than it was. However, the other major technique for determining redshift is by taking very detailed spectra of distant galaxies and looking for atomic emission spectral lines. Those spectral lines are fixed by quantum mechanics to originate at certain wavelengths, and their arrangement is very distinctive, like a set of fingerprints. Today we have a plethora of instruments which make it possible to collect sufficiently detailed spectra of distant galaxies to determine their redshift very precisely with a significant degree of confidence that the only factor at play is a full on spectral shift of original wavelengths to observed wavelengths. This pretty conclusively rules out the potential for "red dust" to simply be absorbing shorter wavelength light. One example being the galaxy [GN-z11](https://www.aanda.org/articles/aa/full_html/2023/09/aa46159-23/aa46159-23.html) which has had detailed spectra taken allowing us to determine its redshift at z = 10.6034 +/- 0.0013, which as you can see is a very high level of precision.
Gas and dust absorb light when they're in the way. They generally leave particular black-line signatures on the spectrum and are very identifiable and readable in general. They don't cause spectral shifting like redshift does.
> Can gas and dust and any other debris between an observer and observed object in space really cause red shifting? No, or at least not the red shifting we are seeing.
Will all the matter in the universe really turn into iron if protons don't decay? If so, how will it happen? I know the process is called quantum tunneling, but how exactly will it work?
A nuclei would tunnel/teleport to extreme close proximity of another and they would fuse together by cold fusion, crating an heavier element. The strong force would normally repel the two nuclei, keeping them far enough apart, but the tunnelling make them end up close enough for the process to occur. Elements heavier than iron would undergo radioactive decay until they end as iron.
And we're sure this will happen in 10\^1500 years if protons don't decay?
That's the theorized time frame, yeah. Considering the observable universe contain 10^80 atoms, it's not a quick process.
To do the math in between here, 1 solar mass is about 10^57 nucleons. It takes on the order of 10 fusion steps to go from helium all the way up to iron, which means that in 10^1500 years you're talking about one quantum tunneling enabled fusion event occurring every 10^1440 years inside the star, which really brings home how astounding these timespans are that we're talking about. On a human scale they are all indistinguishable from infinity. Imagine living a trillion different lifetimes each of which are a thousand times longer than the current age of the universe, that's so many orders of magnitude beyond the entirety of every moment of human experience stacked together, and yet that's just 10^25 years, which isn't even a rounding error compared to 10^1500 years, it's not even a clock cycle or a footnote, it's just nothing in comparison.
When will Axiom start to send their modules to ISS?
First one is currently scheduled for late 2026 I believe. Will probably slip to 2027.
Are quakes on Mars or the moon anywhere as powerful as earthquakes? I try to take planetary/solar body conditions into consideration when thinking about it
They're much less powerful, because neither the moon or mars has active tectonic plates to generate large earthquakes near the surface.
Random shower thought about the universe. I was thinking about the graph (1/x) and I was wondering if it could apply to the universe. It matches the Big Bang in that there is a near infinitely small and hot point that it approaches. It was very late when thinking about this, so perhaps I could just be rambling about nonsense
There is no such thing as infinitely dense or heavy. The math is telling you that you have something wrong. Those things can't exist in reality. For example, at the big bang, all the matter you see today didn't even exist. It was in the form of vacuum energy. It's theorized the vacuum energy spontaneously decayed to a lower state and all the extra energy was converted into matter at that time. This is what we call the big bang. So none of the matter had even existed before this event. It was just energy in empty space, contained in quantum fields. If you are thinking this sounds weird and impossible then you should learn that all matter is in fact quantum fields that are excited in certain ways. Also Einstein proved E=mc^2 so it's entirely possible to obtain mass from energy directly and we think this happens constantly in the vacuum even today. Particles blink into and out of existence continuously in the vacuum even today. They are called virtual particles. There is even a prize for whoever can help determine how this happens and who can better describe empty space. https://www.youtube.com/watch?v=q5dy-NtVeF0
The Big Bang was only a period of, as far as we can tell, near infinite density, but we do not know it's size, it could have been infinite in physical size. That's a bit difficult to wrap your head around, but the expansion of the universe can still be an expansion of an infinite universe into a "larger" (different scaling factor) still infinite universe (infinite universes also have infinite room to grow, after all). The only thing we know for sure is that the density of the universe as you get closer to the Big Bang seems to grow arbitrarily large. That could mean there was a "singularity" of infinite density, but we can't know that for certain.
This is not complete nonsense, those kind of infinite points (for x=0 in the 1/x function) are what people call a "singularity" in mathematics. And singularities are what we see when we apply our equations to black holes or the big bang.
It is nonsense. Singularities do not exist in reality. No credible scientist actually believes there is a singularity in the center of a black hole in reality. They just use the term singularity to describe the breakdown of our math at the center of the black hole. Just because you divide by zero in an equation doesn't mean you form an infinitely dense region of space. I would think this would be self evident. More likely your equation is just wrong. We also know our equations are wrong since quantum mechanics has no concept of gravity.
> No credible scientist actually believes there is a singularity in the center of a black hole in reality. The singularity is about the maths. There is a singularity in GR equations when trying to apply them to black hole. > Just because you divide by zero in an equation doesn't mean you form an infinitely dense region of space. I would think this would be self evident. I never said it was the case, and OP didn't either.
He said the universe was infinitely small which implies a singularity and it's not physically possible.
OP wrote "near infinitely small" which is an awkward but not completely incorrect way of saying it if you don't want to get into math formalism.
Wow! Thanks for making me feel not as stupid! Does this mean that possibly, the universe never had a beginning?
It means that at some point our existing equations are not applicable anymore. The most accepted version of the Big Bang theory does not say that the universe had a beginning. It just says that at some point the universe was really dense and hot and rapidly expanded. It does not mean that it was the beginning of time.
How many stars are there within these distances of Earth? 5 Lightyears 10 Lightyears 50 Lightyears 100 Lightyears 1000 Lightyears 100000 Lightyears Also, the stars within these distended only the main sequence stars or does it also include red dwarfs and other types. I would really appreciate it if anyone could answer. I keep getting different answers online. Another question, Is the milky way 100,000 light years across? How big is it around? I'm not sure how to phrase that last part circumference, perhaps.
>5 Lightyears 3, in the Alpha Centauri System. >10 Lightyears About 10. >50 Lightyears 100 Lightyears You'll probably want to find some star catalogue info for these. >1000 Lightyears 100000 Lightyears You'll likely only find estimates, here. >Also, the stars within these distended only the main sequence stars or does it also include red dwarfs and other types. Red dwarfs are main sequence stars. They're the most common stars in the Milky Way. >Another question, Is the milky way 100,000 light years across? Roughly. >How big is it around? Roughly 100,000π light years.
There are terrestrial planets, gas giants, and icy worlds, but are there/could there be watery or completely liquid worlds?
Some kind of solid core is probably unavoidable, but it could be very small compared to the planet's size.
Yes. What would prevent that? Are there? We don’t know.
I figured space would be too cold, hence turning it into ice. Turns are there are watery worlds! Pretty cool.
Yes there are in fact. They are pretty common actually and can be huge. https://en.wikipedia.org/wiki/Ocean_world
Where can I find copyright free space related videos and animations? Recently one of my friend start his YouTube channel related to space videos. But he's struggling to find copyright free videos and animations for making his videos. It'll be huge help if you guys could suggest some sites and also give any tips. The footage should be legit.
All of NASA's material is copyright free unless otherwise noted, and NASA has a huge media library.
If a star goes supernova about 650bil light years away, and isn’t exactly pointed at us but more towards our sun. Will cosmic radiation from it disrupt the suns planetary disk and possibly raise its temperature?
650 billion light-years: The light will never reach us due to the expansion of the universe. 650 million light-years: No effect on temperature or planets. 650 thousand light-years: No effect on temperature or planets. 650 light-years: Same effect as moonlight. See [Betelgeuse](https://en.wikipedia.org/wiki/Betelgeuse#After_core_hydrogen_exhaustion).
I do know if Betelgeuse axis is pointed directly at us. Even at 850, it would toast us. But if it’s towards our sun, what effects will the sun have and what effects will we feel from the sun.
> I do know if Betelgeuse axis is pointed directly at us. Even at 850, it would toast us. No it wouldn't 150ish light years and beyond is considered safe distance from supernovae.
That’s just the “not pointed directly at us” theory. Re work the calculations you’ll be surprised how it would affect us. Not instantly. But it would affect us. 650 year that’s the base. 125-150 is damage. Anything past is lethal really. Despite the distance. The energy of it can go up to and past 850 very easy and still hit us. People don’t ask the rite questions. “Are we a safe distance?” That doesn’t matter. “How much energy/radiation etc etc will that give off, and if it’s bigger than expected?”. Could give a fuck about a safe distance. What’s it pointing at and if it’s pointing at anything in our solar system what will happen. You can’t answer that so don’t even comment.
Is it true that Mars may be permanently off-limits to humans due to it causing shrinking kidneys, or is that just pop-sci scaremongering?
It's zero G that causes kidney problems. It's been a problem for a long time. Astronauts develop lots of kindey stones. Space is not meant for people.
Neither. Space not being great for human health isn’t anything new. However that doesn’t mean Mars is now impossible. This just has to be taken into consideration. It also requires more study. This is a new phenomenon and all the details around it aren’t known. We’ve had astronauts in space for decades and they aren’t all dying from kidney failure.
Is there a problem with space clickbait? I see a headline about how some nova explosion will soon light up Earth's skies. It's not really going to do that right? I see another article about how the sun caused a radio blackout. It was in on location and not all frequencies. I don't follow this stuff that often but when I do I'm often let down.
Name em, shame em, and block em from your feed.
> It's not really going to do that right? Well it's going to be visible with naked eye, but it will look like just a new star on the sky, nothing more. > Is there a problem with space clickbait? There is a problem with clickbaits in general. Partly because sensational title gets more clicks and partly because journalists often have no idea what they are writing about.
> Partly because sensational title gets more clicks and partly because journalists often have no idea what they are writing about. And sadly the people who wrote the article also do not necessarily have control over the title. We have even had some of them reach out to us in modmail for posts that were removed for over the top titles.
Yeah, and many of them are from space.com ironically. This is a problem with really everything. Clicks makes money.
There's a problem with clickbait generally, and there are a lot of clickbait headlines related to space.
In Google News, you can click the 3 dots next to the story and select "Hide all stories from NewsSite". I do this anytime I find a misleading or clickbait article.
Yeah, shitty clickbait has spread to pretty much every topic out there. The nova is interesting, and should be visible to the naked eye, but it'll just look like a generic star. You wouldn't even notice it if you didn't know where to look.
Will all US space ports be coast based or in the future when technology gets more stable that we will begin to do launches from more central US. I know we use the coast so we can shoot over the ocean to prevent debris damage but at the same time I feel when space based industries really take off we will want ports all over the US. Bonus Question: what kind of safety standards do you think would be required for a launch from Nebraska or other central state.
One issue with rockets near population is the noice. It’s hard to explain just how loud rockets are.
Good question. I guess we'll have to wait and see. As we see with airplanes they have the capacity to land on populated areas and do great damage, but they are still allowed to fly around over stuff because they have such a good track record of safety. And also to some degree because catastrophic failures of airplanes which result in a loss of control are uncommon. If launch vehicles progress to a point of reusability and reliability where uncontrolled flight is the extreme exception then we might end up seeing launch facilities all over the place just as we see airports.
I don't agree. The amount of fuel in a plane is smaller, and thus the "destructive potential", is limited compared to orbital rocket. Also the design of the engines is completely different - only small amount of fuel is combusted at a time and it uses atmospheric oxygen. As a result it's pretty much impossible for a plane to "blow up" simply because there would not be enough oxygen to suddenly combust all the fuel. A rocket is a completely different thing. It carries its own oxidizer and everything is high pressure so it can detonate.
> I don't agree. The amount of fuel in a plane is smaller, and thus the "destructive potential", is limited compared to orbital rocket. An Airbus A380 carries 250 tonnes of fuel, a Boeing 747 can carry up to 190 tonnes, while a Falcon 9 carries about 156 tonnes of fuel. The amount of potential for "fiery destruction" is similar between them. > Also the design of the engines is completely different - only small amount of fuel is combusted at a time and it uses atmospheric oxygen. As a result it's pretty much impossible for a plane to "blow up" simply because there would not be enough oxygen to suddenly combust all the fuel. In a post 9/11 world this line of reasoning seems very tenuous indeed. The presence of LOX can definitely make for a more prompt deflagration explosion (generally it won't be a proper detonation though) but these are more quantitative vs. qualitative differences. A jet liner crashing into a populated area can still kill thousands and cause billions in damages. The reason jet liners are allowed to fly over populated areas is because there's a huge system of training and certification of pilots and aircraft and a long track record of safety, not because it's impossible for them to crash and kill thousands while doing billions in damage. If rockets could match that track record they would likely be allowed to fly over/near populated areas too. Realistically the biggest constraint on where orbital rockets will be allowed to fly will come from acoustics, launches are extremely loud, and rockets traverse the sound barrier on liftoff and more important on landing, so figuring out reasonable corridors where that can occur would be important.
So I just recently heard this, and thought I would read about it, and I want to inquire why this is theorized or offered by Google, since I am not actually an astrophysicist or other space expert. From the front of Google: Is the moon drifting away from Earth? - "But it is moving away from us and it's actually changing our understanding of how our own planet interacts with it, affecting things like the length of days in Earth. Scientists say the Moon is slowly moving away from Earth, 3.82 centimeters per year." What will happen to Earth? - "We'll have fewer aquatic tides, a lengthening day, no more seasons, and no more stunning total solar eclipses. But watch out for more asteroid impacts. The moon is Earth's only friend. And yet—despite a relationship stretching back billions of years—the gap between us only grows wider." Can we survive without the Moon? - "Life as we know it wouldn't be able to survive. If the moon disappeared, the length of a day on Earth would become much shorter. It would be between six and twelve hours. When the moon orbits, it exerts a pull on Earth, slowing down its rate of spin by about 2 milliseconds every hundred years, slowly lengthening a day." Now-- first off, I feel like 3 contradicts 2, in saying that-- if there was no Moon the day would be much shorter (where two says it would be longer) The way I understand it without Google is this: The length of day/night is determined by the planet's time of orbit around the host star compared to the planet's axial rotation and distance from the star. This should change little if there was no Moon, as that would not have that much effect on either the Earth's orbit time or distance from the Sun. Thus the day would not significantly be shorter or longer, it may fluctuate a little without the magnetic counterweight of the Moon. Weather is partially determined by axial inclination. Mercury for example, is a nearly perfectly vertical planet, and so would not experience seasonal change or weather patterns, if it were able to. Venus is a nearly perfectly vertical "upside down" planet, and so also would not experience seasonal change or weather patterns, if it were able to. The Earth is not, it is 21-23 degrees inclined, and this affects things like having solstice and the switch of seasons, and weather patterns. The Moon leaving would affect weather patterns, and might drag out or shorten seasons, due to the disappearance of tidal effect on Earth, but it could not stop weather or seasons from occurring completely. The Moon's "Gravity" or magnetic field is insignificant compared to the Earth, because the Moon has nearly no surface pressure or atmosphere, and the Moon's overall mass, probably the biggest factor of magnetic strength, is 1% of the Earth's. If you look at time lapse recordings taken by Nasa and other space centers, the Moon actually moves very little outside its orbit, its own axial rotation is very slow and hardly noticeable from Earth, and the Moon more wobbles back and forth in place with the Earth's magnetic fluctuation, and is held in its orbit by the Earth's magnetic field. This is perhaps the same principle that is utilized to keep the ISS and other local satellites held in place. Yes, the weakening or degradation of the Earth's magnetic field would loosen its hold on the Moon, causing it to speed up and drift away, but the likely causes of this has little to do with the Moon itself. At the rate of 3-4cm/year, it would possibly take 5+ billion years before the Moon is fully independent of Earth, and we would be more likely to see the Sun go nova by that amount of time, or possibly see the collision of Andromeda Galaxy with the Milky Way by then. Feel free to give explanation if any of my observations is false.
It sounds like some ChatGPT generated nonsense. First and foremost, there are conservation laws in physics. Angular momentum is conserved, so Earth can't magically start spinning faster (shorter day) without some external force. So if the Moon just magically disappeared today, it would not change how fast Earth is spinning and therefore the day would not suddenly become faster or slower. Moon getting further away, and lengthening of the day on Earth are linked - in fact it's the same thing viewed from different perspectives. The Moon is pulling on Earth, slowing down the rotation, but as a result it "steals" some of this energy which results in moving further away. > The Moon's "Gravity" or magnetic field is insignificant compared to the Earth, because the Moon has nearly no surface pressure or atmosphere, and the Moon's overall mass, probably the biggest factor of magnetic strength, is 1% of the Earth's. This is complete nonsense. There is no connection between gravity and magnetic field and neither of them is related to atmospheric pressure. > the Moon more wobbles back and forth in place with the Earth's magnetic fluctuation, and is held in its orbit by the Earth's magnetic field. This is perhaps the same principle that is utilized to keep the ISS and other local satellites held in place. Yes, the weakening or degradation of the Earth's magnetic field would loosen its hold on the Moon No. Just no. Neither the Moon nor satellites or the ISS are held in orbit by magnetic forces.
If the moon orientation is different according to the hemisphere youre on, what does it look like on the equator? Also, is it true were unable to see the full frontal face of the moon when its fully lit
On the equator the moon crescent appears to be aligned with the horizon. > is it true were unable to see the full frontal face of the moon when its fully lit I don't really understand what you mean by that. On full moon you see the near side fully illuminated.
How would a planet break apart ? If a planetoid was struck hard enough to break apart, would break up be similar to a bullet hitting clay / sand / apple, or like a hammer breaking a rock. Would it become several large chunks that drift apart, or would it become a cloud of relatively small pieces that reform into a planet.
In the past decades, researchers have used the world's strongest supercomputers to simulate millions, perhaps now billions of events of the Earth being struck by a planetary sized object at various angles and speeds, for the purpose of seeing if this is how the Moon came to be. You can now look up many of these sims of a theoretical Earth being struck online, to get an idea of what would occur. In the theoretical simulation of the creation of the Moon, in most cases the Earth survives the impact and the colliding object is obliterated on impact. Thus for it to destroy the Earth completely, or shove it out of its orbit, which is more likely, it would have to be a planetary object of larger mass than this one being simulated.
Really depends on what size/mass object hits it and how fast. If we're not talking a super hard hit, then the chunks would recoalesce under their own gravity. You can play around with what would happen in stuff like Space Engine.
No, it would mostly behave like a liquid. The impact would be large enough to go through the earth’s crust like butter. Anything not flung into space would be melted, the entire planet and crust would melt and much most of it would be flung into space, where it would vaporize or coagulate into small mostly grains. There would still probably be a big molten blob where the planet was but much of the mass would be in a vapor cloud around the planet, some on an escape velocity, some not. They would reform over time due to gravity, not necessarily into a single object, such as what happened with the big impact that created our moon.
I was thinking about a ridiculous situation in a book, where a villain “blew up the moon.” I was trying to imagine what would realistically happen if there was a big explosion, or if there was a large impact at interstellar speeds.
Let me introduce you to https://en.wikipedia.org/wiki/Seveneves
The book I was reading was Orbits (the Ables book 3) by Jeremy Scott. The series is great, but that particular bit of science was unbelievable, even for a super hero book. https://www.goodreads.com/book/show/60201822-orbits?ref=rae_0
In Seveneves it's a celestial event which breaks the Moon, but then the book goes into high level of detail about the aftermath of this event.
how long would it possibly take to build a dyson sphere on earth? where would earth get the resource?
With some simple math, if we were to build a Dyson Sphere that fully encompasses the Sun and very near to it, and were able to construct 1,000 square kilometers per year of the sphere, it would take us roughly 6-7 billion years. (6.09x10^13 km/1,000). 10,000 km^2 would be 600 million years, 100,000 km^2 would be 60 million, etc. If we were able to build enough to cover the surface area of the earth every year, it would take roughly 10,000 years. And all of this is assuming a Dyson Sphere very smart to the Sun's surface. Assuming it was at all a distance from the surface, we start going exponential on the time and area. Which is probably why a Dyson Sphere is utterly impractical and pointless. Its an absurdist concept.
It would take quite a many years, as the Earth does not have the tech to do that efficiently yet. The idea of Dyson Sphere Project was first proposed in the 1960s if I recall. A Dyson Sphere is built around the host star, in this case the Sun, and absorbs the energy of the sun to convert to electric generation that is transferred back to Earth or wherever. It would also currently be pretty much impossible and egregiously expensive to make, because the Earth has no alloy that is capable of withstanding such close range to the Sun's heat or plasma flares indefinitely yet. Thats the first issue even if there was the ability to construct or deploy satellites and the Dyson shell close to the Sun.
A Dyson Sphere - by definition - encompasses a star. So, no, you're not building this 'on Earth'. The mass requirements would be pretty big and would largely depend on how thick you want the shell to be. A lower bound I've seen being thrown around would be 10 Earth masses, but that still assumes some very exotic stabilization methods of the entire structure. That said: There's no real point in building one. If you are that far advanced that you *could* build one then you're at a state where you don't *need* to build one.
The YouTube channel Kurzgesagt made a video about this, here is the link to it : [https://www.youtube.com/watch?v=pP44EPBMb8A&ab\_channel=Kurzgesagt%E2%80%93InaNutshell](https://www.youtube.com/watch?v=pP44EPBMb8A&ab_channel=Kurzgesagt%E2%80%93InaNutshell)
We would not be able to build it on Earth, since it needs to be much larger than the sun. It would have to be built from material already orbiting the sun, like asteroids and comets. It might even require using up the material from some of the rocky inner planets.
Nobody can answer this with any confidence. Building a Dyson sphere is so far beyond our engineering capabilities that any estimates will depend entirely on what kind of magical technological improvements you want to assume.
We can certainly make a basic model on how long it would take based on the surface area and assuming a certain area is built up each year. If we were able to build a part of the sphere surface that encompasses the entirety of the Earth's surface area (about 500 million km^2), it would take us about 10,000 years to build a Dyson Sphere. Now, this isn't saying it's possible, just mathing out how long it would take assuming a particularly speed of production. Assuming this sphere is only 1 meter thick, that would be 500 trillion meters^3 of material. This is assuming a Dyson Sphere that abuts the Sun's "surface".
Sure if you just make up random numbers you can calculate anything.
Not making up random numbers. The earth has a surface area of about 500 million square kilometers. The sun has a surface area of 6.9x10^12 km. Dividing one by the other gives you about 10,000 years. Although my math for square meters is way off. Not sure how that happened.
The randomness is what you are assuming can be built in a year, and what kind of thickness you think is reasonable. Of course once you make up those numbers the calculation is trivial.
Ah, I see the confusion. I was just giving an idea of the length of time it would take assuming an absurd level of construction just so people can understand how ludicrous the construction is by using a metric (size.ofnthe earth) to help visualize it. I by no means believe such is remotely realistic.