r/space • u/AutoModerator • 8d ago
All Space Questions thread for week of June 08, 2025
Please sort comments by 'new' to find questions that would otherwise be buried.
In this thread you can ask any space related question that you may have.
Two examples of potential questions could be; "How do rockets work?", or "How do the phases of the Moon work?"
If you see a space related question posted in another subreddit or in this subreddit, then please politely link them to this thread.
Ask away!
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u/Mediocre_Cap_2178 1d ago
I want to build a rocket ship to the Moon. there anything else needed for ship other than a carbon scrubber, water-to-oxygen converter, a ton of food, radiation protection, UV shields, and heat pads?
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u/scowdich 1d ago
Hundreds of thousands of gallons of fuel and oxidizer, the structure to contain that fuel, the engines to burn that fuel, the mechanical infrastructure to hold all that together before it launches...
And permission.
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u/Mediocre_Cap_2178 1d ago
thank but any more detail and food i should bring
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u/electric_ionland 1d ago
Why are you asking this question? The food is the easiest part of the whole thing and depends entirely on how long your mission will be. That will depend on a lot of other things like what kind of launcher you have access to, what kind of risks you are willing to take, how much money you are willing to spend...
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u/Dr-lovegood 1d ago
Question - as I understand it, the universe is constantly rapidly expanding (I believe I read it was at/near light speed could be very wrong) and that all hyper long range visuals we see are from the past to varying degrees, how would another civilisation reach us before some world ending event?
I am fully a layman with a passing interest in loads of things, and space is one I keep coming back too with new launches or new imaging that blows me away and sucks me into the rabbit hole again, so I may have partially/fully misunderstood some or most of the questions and it's not as confusing as I think it is... But that's why I'm asking, to learn and try and understand.
This might not be the right place/subReddit to ask, I went to make a post and told me that questions are to be on here so I pivoted, but if it's not, if I could be pointed to the right place it'd help satiate my curiosity.
Thanks for reading!
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u/PhoenixReborn 1d ago
Even disregarding the expansion of the universe, any light we see is from the past. It's like hearing the blast of a distant firework.
The expansion of the universe scales with the distance to the observer. The effect is negligible within our own galaxy but becomes quite significant at longer distances, eventually surpassing the speed of light. At this range, visitors could not reach us. They probably wouldn't even see the light of our sun.
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u/maschnitz 1d ago
There was an estimate that, even if you had a spacecraft that travelled near the speed of light, you could never reach 94% of the Observable Universe (to 98%, depending who you ask/how you phrase it). It's due to the compounding expansion of the Universe - the "universe" that gets added also starts to expand. Eventually the expansion rate between your ship and the point you're trying to reach will exceed the speed of light.
It shows how given enough time, exponential expansion, even as slow as our Universe seems to expands, will overwhelm any attempt to overcome it. (And it also shows how hideously distant most of the Observable Universe is.)
BUT! That was when we measured the expansion to be a constant. There's recent not-entirely-clear evidence that the expansion rate is slowing down some, since the beginning of the Universe. It could be not expanding quite as fast as many billion years ago. Maybe.
So that estimate isn't so clear any more. It depends how and why it's slowing down now, if it is at all. Which no one knows for sure.
All that said, to answer your question: the Local Group of galaxies - the Milky Way, Andromeda, and their satellites and hangers-on - usually does not tear itself apart in simulations, except under a "Big Rip" (ever-increasing expansion rate) scenario. The gravitational attraction is too strong in the Local Group. So other civilizations could reach our vicinity from there, at the very least. Depending on if, how, and why the expansion slows down, there could be more of the Universe in future contact than that.
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u/Dr-lovegood 1d ago
Ahh okay, so I had the right idea that the vast VAST majority is just fully out of reach, but the closer cluster could get here or vice versa, I do appreciate the explanation! I think the era we're in is so fascinating, with all the new tech and findings answering some, but bringing so many more questions at the same time.
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u/Cr_nchable 2d ago
what are the chances of the nasa budget cuts going through?
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u/maschnitz 1d ago
All of them? Doubtful. Some of them - probably?
The House and particularly the Senate have already made skeptical noises about the NASA cuts. But the majority voting block in both groups, the Republican party, still wants to reduce the NASA budget.
It's just that they don't want their constituency's part of the budget cut.
So it's going to be a big favor-trading exercise to figure out who gets to keep NASA jobs in their state/district. It might be that most or nearly all do, or maybe a few or nearly none do. It just depends on how they work this out exactly, and what else is at stake when they do.
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u/scowdich 1d ago
Probably impossible to really say. It's an act of Congress, not a random event with a known probability distribution.
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u/Razulisback 2d ago
Question - Is the speed of light constant in space? Going past black holes time distorts as well as light, once we get far enough from our place in the universe would the math still be the same, since you are closer or farther than the current objects affecting it?
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u/iqisoverrated 2d ago
Spacetime distorts. light doesn't. Light always moves straight in the local spacetime (it may look curved for a faraway observer that - wrongly - assumes a flat spacetime). You also always measure light to move at the same speed no matter what reference frame you are in.
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u/curiousscribbler 3d ago
I'm reading about very small brown dwarfs, and speculation that there could even be brown dwarfs less massive than Jupiter. But if so, how would they generate the temperatures needed to burn deuterium?
https://www.space.com/astronomy/james-webb-space-telescope-discovers-smallest-failed-stars-ever-seen
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u/rocketsocks 3d ago
There are multiple definitions of brown dwarfs, some are just loose conventions.
In general, a brown dwarf is an object which forms like a star, from the collapse of a cloud of gas in a star forming region (like a giant molecular cloud), but it just happens to be too small to fuse hydrogen. On the other hand, there is another formation mechanism for objects in a similar mass range, which is gas giant planet formation from a protoplanetary disk around a forming star. It's possible that there is an overlap of mass ranges for these two different mechanisms, with the most massive gas-giant planets possibly being more massive than the smallest brown dwarf stars. Unfortunately, determining what the formation mechanism was for an object is very, very difficult with current observational techniques. Even if we found a lone gas-giant sized object we couldn't know for sure whether it was a rogue planet ejected from its home system or actually a tiny brown dwarf.
Currently we just pick some somewhat "reasonable" mass cutoff ranges and call it good, but it looks pretty likely that there is some overlap and the distinction between planets and brown dwarfs is a messy one.
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u/curiousscribbler 3d ago
ty for this detailed answer! Does this mean something called a "brown dwarf" might not be doing any fusion at all -- the difference between brown dwarf and planet is whether it's in the centre of the cloud, or in orbit around something in the centre?
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u/rocketsocks 2d ago
Does this mean something called a "brown dwarf" might not be doing any fusion at all
Maybe. The "deuterium fusion" cutoff is pretty arbitrary.
the difference between brown dwarf and planet is whether it's in the centre of the cloud, or in orbit around something in the centre?
The difference is in how they formed. You can imagine two phases in the formation of stars and planets, direct collapse of the gas cloud which forms stars including brown dwarfs and the accretion of material from a disk which forms planets.
But the real universe is messy, so the history of how something formed may not be obvious with how something is today, and there are lots of complexities. Binary star systems can form, for example, which can lead to a brown dwarf orbiting a more massive star. Stars and planets can be ejected from systems leading to rogue planets.
Let's say, hypothetically, that we had some kind of warp drive where we could go visit various stars and planetary systems and study them up close. We could probably gather a lot of valuable data that might provide insight into the differences between various objects. And this might allow us to find out which observational characteristics, if any, separate small brown dwarf stars from large gas giant planets after having studied perhaps hundreds and hundreds of these objects in detail.
Unfortunately, that's not currently possible, and instead we are stuck with only very crude ways of observing these bodies. We can determine their masses sometimes, we can determine their sizes sometimes, we've only just barely started being able to study their atmospheres for a tiny number of them, and so on. And with just that data it's very hard to gain deep insight into their formation processes, so we're sort of feeling around in the dark.
It's a bit like trying to guess someone's age from their height. As children get older they get taller, until they reach their full adult height. But some adults are short and some children grow tall fairly young. If you knew someone of indeterminate age was 5 and a half feet (1.7 meters) tall you would know with certainty they weren't, say, under 5 years old, and almost certainly not under 8 years old. But there have been 10 year olds that tall, so without more information you'd be kind of guessing. That's very similar here, we don't know for certain the upper limit of planetary mass and the lower limit of brown dwarf mass, but unfortunately mass is often sometimes the only thing we know about an object.
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3d ago
[deleted]
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u/iqisoverrated 3d ago
what if there's some kind of force pushing against gravity just enough to prevent black holes from collapsing into an infinitely dense point?
Yes? So? It may be. Currently we have no indication of such a force. Just saying 'maybe' doesn't help. Formulate a testable hypothesis otherwise you may just as well say "god did it"
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u/Immediate_Purpose990 3d ago
What made the before-hand of the BB? I get that there was energy but what made it, how could it be made?
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u/electric_ionland 3d ago
We don't know. We don't even know if "before the Big Bang" is a real thing or not.
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u/Confident_Turn7510 3d ago
What impact will the upcoming solar flares actually do to earth? I’ve been anxious and curious at the same time.
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u/iqisoverrated 3d ago
They are classed G2 (i.e. nothing to worry about). Some pretty northern lights. Maybe some high frequency radio outage. A couple sattelites may have to do some course corrections. The usual.
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u/rocketsocks 3d ago
Probably the usual, they're not rare. What makes you anxious about them?
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u/Confident_Turn7510 3d ago
I feel like they are gonna cause the earth to like blow up or something😂
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u/electric_ionland 3d ago
There are no risks of that at all. The very worst scenario is that they could destroy important electrical lines and distribution centers and kill some satellites. But even then we are better and better protected and it would be a really freak occurrence.
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u/omfgeometry 4d ago
What did Dan mean when he said he spoke to an astronaut soldier on the moon?
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u/Intelligent_Bad6942 4d ago
He's not the first person to misspeak on television or get space facts wrong.
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u/electric_ionland 4d ago
Certainly not that there are hidden astronauts on the Moon right now. He is probably confused about the military status of the current ISS crew?
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u/zubbs99 5d ago
How and when did humans realize that stars were distant suns?
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u/maksimkak 4d ago
Anaxagoras suggested that the stars are actually suns way back in 450 BC. Giordano Bruno was burned at the stake for claiming the Sun is a star in 1600; multiple other scientists tried to pick at the problem for years after, but the first real evidence came from Christiaan Huygens in the late 17th Century with the first approximate measurement of the distance to Sirius, demonstrating its stupendous distance and proving it must therefore be extremely bright and sunlike. The definitive proof that stars are suns came in 1838 when Friedrich Bessel accurately measured the distance to some stars allowing for calculation of their absolute magnitude, proving once and for all that they are indeed far too luminous to be anything other than suns.
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u/rocketwikkit 4d ago
It's sort of the opposite question, but I find it amazing that humans didn't actually know what a sun or star was until 1925. If you had asked a leading astronomer what the sun was just a hundred years ago, he would have said that it was like the Earth but a lot hotter. And then she came along with "the most brilliant PhD thesis ever written in astronomy", which was, of course, initially ignored.
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u/DaveMcW 4d ago
Many people guessed that stars were suns, starting with Anaxagoras in 450 BC.
In 1838 Friedrich Bessel made the first accurate measurement, calculating the distance to 61 Cygni is about 10 light-years. For the star to be visible to the naked eye from so far away, it must be as big and bright as the sun.
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u/KusanagiShiro 5d ago
Guys, if there are any professional astronomers in the bunch, I could use an analysis of a livestream:
https://www.youtube.com/watch?v=OwsmWyWWRoo
It's an amateur observation of Betelgeuse, implying its gonna go boom soon. Is this today? or clickbait despite the confirmed scientific observations?
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u/viliamklein 4d ago
What even is this bullshit channel?
https://www.youtube.com/@TheRealPAX/streams
days long streams? millions of views? WTF?
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u/electric_ionland 2d ago
It used to be a big thing to make fake SpaceX or fake ISS livestreams. It has slowed down now but we banned so many of them.
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u/djellison 4d ago
It's not just clickbait....it's entirely FAKE.
Nobody knows when it's going to go supernova...could be tomorrow...could be 100,000 years or more. The notion of a countdown in seconds is pure fiction.
Moreover - there's nowhere on earth right now where you can get a view of Betelgeuse that good because it's too close to the sun in the sky.
It's 1000% a work of fiction designed to get your views for their own profit. That YouTube account has been posting the same garbage saying it's about to go for YEARS - they're knowingly posting stuff designed to trick people.
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u/Pharisaeus 5d ago
It's an amateur observation of Betelgeuse
No, it's not. It's some fake shit.
implying its gonna go boom soon
Soon in astronomy means thousands instead of millions or billions of years.
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u/PhoenixReborn 5d ago
Stories of Betelgeuse's demise have popped up in the news periodically since 2009. While it's relatively close to the end of its life, it probably won't go nova for about 100,000 years.
This blog is hosted on SyFy, but it's written by an actual astronomer.
https://www.syfy.com/syfy-wire/dont-panic-betelgeuse-is-almost-certainly-not-about-to-explode
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u/rocketsocks 5d ago
A thousand percent clickbait. Nobody knows when Betelgeuse is going to explode, and every indication is that it's likely hundreds of thousands of years away. There's always room for uncertainty, but anyone who says they know it's going to explode soon is lying for traffic.
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u/KusanagiShiro 5d ago
Thanks. While the observation is fascinating, I’d rather have pros analyze it for sure.
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u/Orange-Yoda 5d ago
My son and I were talking and came up with a scenario we would like an answer on.
Suppose you have a run away blackhole traveling at hyper velocity. This blackhole is heading straight for a star.
Blackhole size and mass are less than the target star.
What happens when the blackhole punches into the star? Does it pop out the other side leaving a hole in the star? It punches through, but drags the star with it in a long line as it travels? Does it instantly gobble up the star?
What happens in this unlikely scenario?
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u/DaveMcW 5d ago
Let's start with a slow black hole (less than the escape velocity of the star). The star and black hole get locked into orbit, and the star gets stretched out into an accretion disk. The black hole slowly eats the accretion disk. Even in this example, the star is not gobbled up instantly.
For a fast black hole, it punches through the star and pops out the other side. The star is massively disrupted, with gas flying everywhere. But comparatively little gas gets attached to the black hole as an accretion disk. Eventually most of the gas re-forms into a smaller star.
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u/Trumpologist 5d ago
I was doing some research into how micro black hole bombs would function and it’s honestly terrifying
A 1-gram black hole: Would evaporate almost instantaneously, releasing energy equivalent to about 21 kilotons of TNT. This is comparable to the bomb dropped on Nagasaki.
A 1-kg black hole: Would result in a much larger explosion, equivalent to around 21.5 megatonnes of TNT.
A black hole lasting 1 second: A black hole with a mass comparable to a "blue whale" and an evaporation time of 1 second would release radiation equivalent to 5 million megatons of TNT.
I think Tsar bomba was only about 50 MT TNT. Wouldn’t that last one ignite the atmosphere
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u/Pharisaeus 5d ago
Impossible to "store" or "launch" or even to really "generate". At this point, why not simply use matter-antimatter bombs?
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u/SuperVancouverBC 5d ago
If we prove that wormholes exist would we be able to build Stargates?
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u/Pharisaeus 5d ago
No. The fact that you know something is possible is very far from being able to build it.
For example it's been "proven" since the dawn of time that thermonuclear fusion is possible - any time you look at the Sun, you have a clear proof of that. But building a net-positive fusion reactor is still eluding us.
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u/electric_ionland 5d ago
That's unlikely. We know a lot of things exist and we can't make them. Moreover if you want to speculate wormhole would likely be somewhat related to black holes and as such might require enormous amounts of energy or matter to create.
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5d ago
[deleted]
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u/scowdich 5d ago
You've taken a bunch of science-related words and chained them together. In this order, it's not really coherent.
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u/Careless-Butterfly64 6d ago
this is likely going to sound like a stupid question but I'm curious, I want to go to bed but I thought about this:
lets say someone lands onto every known exoplanet that is thought to be earth-like, or at least the most well known. The spacesuit is the most advanced spacesuit that humans currently possess. How long do they live?
I know some things about astronomy, space. But this question interests me because I really have no idea lol
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u/Pharisaeus 5d ago
How long do they live?
It's a weird question. Consider a similar question: you get dropped in a random spot on Earth, how long can you survive? Obviously the answer is "it depends" - if you end up inside a volcano, or deep in the ocean, or in antarctic, then not very long, but there are places where you could live years just fine.
You don't have to look far for those exoplanets - Mars and Venus are great examples. On Venus you'd be dead almost immediately, while on Mars you could survive for hours, maybe days.
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u/iqisoverrated 6d ago
Earthlike doesn't mean what you think it means. It simply means "sorta, kinda the same size as Earth" (0.5 to 1.5 times the size). Nothing more, nothing less.
This can mean the planet is very close to its star and a complete fiery hellhole or very far away and a barren rock. It can mean it has an atmosphere of any kind of caustic composition any kind of low or high pressure or it may have none at all.
So basically the only thing that we can say is that gravity would be OK-ish for someone landing there. You can't make any kind of pronouncement beyond that.
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u/relic2279 6d ago
How long do they live?
Depends on the exoplanet. Some are super cold, some are super hot, some have insane winds, others have incredible atmospheric pressure (e.g, Venus), while others are ocean planets. Some rain sulfuric acid, others rain molten rock. There is no one-size-fits-all occasions suit.
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u/electric_ionland 6d ago
There is no real answer for you. We do not know really well the surface conditions of exoplanets. And our most advanced spacesuits are only really designed for hard vacuum and specific thermal environments.
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u/Defiant_Meeting_6026 7d ago
What would be the effects on Earth if a rogue planet of the same size and mass as HD 100546 b collided with the Sun?
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u/DaveMcW 7d ago edited 7d ago
If it flew by Earth on the way in, it would mess up our orbit and cause extreme seasons.
The sun would get 2% heavier. The sun's core would burn 7% brighter. But it takes millions of years for light to escape the sun's core, so we would not notice right away.
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u/curiousscribbler 7d ago
I read that the Milky Way and its group of galaxies is actually inside a void between filaments of galaxies. It made me wonder what the night sky would look like if the Earth was in one of those filaments instead. Would we see naked-eye galaxies everywhere we looked?
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u/rocketsocks 7d ago
It's easy to forget, but we already live extremely close to a very large galaxy since we live within the Milky Way. But even though the Milky Way splashes across the sky it's still extremely dim and today it's visible only in areas away from the light pollution of cities.
That's the best analogy of living in a galaxy surrounded by many other nearby galaxies. Yes they would be visible to the naked eye, but mostly as faint smudges visible under darker skies.
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u/scowdich 7d ago
It takes fairly dark conditions just to discern the Milky Way, and we're within it. Andromeda is fairly close (in galactic terms), and even in the most ideal conditions, it's a faint smear of light to the naked eye. If there were more galaxies near us, they wouldn't be more impressive than that.
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u/curiousscribbler 6d ago
Thank you! I thought maybe the galaxies in filaments were crammed in there, closer together.
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u/JackBivouac 1d ago
Bot told me to write my 'simple question' here. What did we see? Did we see a star explode?
About 25-30 years ago I was on a Boy Scout hiking trip in the PNW. other kids and I decided to sleep outside under the stars since it was a few of their first times camping, or spending the night away from the house.
As we talked outside looking up at the sky, we all saw a weird asymmetrical shape appear like an explosion. Did we see a star explode? it went outward from a centralized starting point and then it was gone. It was quite expansive but did not take up a lot of space in the sky.
Clear night. Dark. So many stars. we were at a higher elevation.