70% of meteorites from 3 collisions in asteroid belt within past 40M years(skyandtelescope.org)
skyandtelescope.org
70% of meteorites from 3 collisions in asteroid belt within past 40M years
https://skyandtelescope.org/astronomy-news/weve-found-the-source-of-most-meteorites/
60 comments
One thing that always kills my suspension of disbelief in SF movies/books is when ships arrive at asteroid belts and it's like driving through a hailstorm. Space is soooooo empty
For me, it’s the bombs. Real life bombs don’t beep or blink a red LED.
There are localized debris fields though.
Enough to poze a hazard for space travel, but it's not the stationary pieces of rock that we see in movies or games. It's usually fast moving objects that make specific useful orbits dangerous.
https://tvtropes.org/pmwiki/pmwiki.php/Main/AsteroidThicket
There is a nice list here https://tvtropes.org/pmwiki/pmwiki.php/Main/ArtisticLicenseS...
There is a nice list here https://tvtropes.org/pmwiki/pmwiki.php/Main/ArtisticLicenseS...
That was quite annoying in a recent movie sequel that was otherwise relatively hard scifi. Do script writers read tv tropes?
Its baffling how they can reconstruct such an ancient event that happened so far away.
I guess there are just so few interactions in space that it’s pretty easy. Bunch of rocks that have been on the same course for millions of years, and aren’t impacted by air resistance or anything to slow them down.
Wouldn't Jupiter's orbit create some interactions?
Funny. My first thought was: what? 40Mya? That's recent history by astronomical standards!
Yeah that's recent enough some early primordial primates would have seen it.
Give it another 80M years, and perhaps a fine dust could make some fine sunrises on Jupiter.
It makes me think of this: https://www.youtube.com/watch?v=p08_KlTKP50
This pretty much means that there were only 3 large collisions in the asteroid belt in the past 40M years... Which is astonishing considering how busy the belt is...
It's not that "busy" though, is it? My understanding is that asteroids are pretty damn small and very far away from each other. It's always funny to see an "Asteroid Belt" in Sci Fi movies and TV, where it looks like they're flying their spaceships through a raging river of rocks dodging one every second. In reality: if you were standing on any asteroid in the belt, would you even be able to see any other one with the naked eye?
Wikipedia puts the average distance between 'roids at about 600,000 miles, so I'm going with no. Also mentioned is the estimate that the mass of the entire belt is thought to be 3% of weight of the moon. That's crazy tiny, considering how much space it is spread out over.
It would been like seeing an object 1/3000 the size of our moon at twice the distance away.
It would been like seeing an object 1/3000 the size of our moon at twice the distance away.
>Also mentioned is the estimate that the mass of the entire belt is thought to be 3% of weight of the moon. That's crazy tiny
It's worse than that: 60% of that mass is contained in only 4 asteroids, the largest of which is the dwarf planet Ceres. So if you ignore those 4 bodies for a moment, the rest of the asteroids are only around 1.2% of the Moon's mass.
It's worse than that: 60% of that mass is contained in only 4 asteroids, the largest of which is the dwarf planet Ceres. So if you ignore those 4 bodies for a moment, the rest of the asteroids are only around 1.2% of the Moon's mass.
I remember doing the math once years ago and if you presume that all of the asteroids are pure Fe, you have on the order of 100 atoms/m^3 of density in the "asteroid belt."
So you have a gripe about sci-fi for not being realistic about asteroid fields, but the ability to fly a space craft with the agility of a fighter jet on Earth is okay? I love the arbitrary nature every single sci-fi person has in their application of suspension of disbelief. There's a lot of times I end up thinking, "oh I didn't think about that" after someone mentions a hang up they have, and there's other times where I'm laughing at the ridiculous nature while someone else thought it was much more acceptable.
> the arbitrary nature
"Sci-fi" already tells you what's the fictional part of the story: the science/tech, and maybe some fundamental rules around those. Fantasy is where you get to rewrite the basic rules of the universe.
In the span of a few decades we went from no planes to flying at almost Mach 10 in air (X-43) and 600.000km/h in space (Parker probe), and from AM radio to a super-computer in everyone's pocket. So you can bet any person can reasonably imagine that in a few centuries we could be advanced enough to build today's sci-fi. That's because they have a few real anchor points in the history of human civilization or even their own lifetime and an easy assessment of the progress of science between them.
Most people also actually think asteroid belts are that dense. But that's because even basic concepts about gravity aren't immediately apparent from day to day experience. Basic grasp of gravity will never allow you to believe it naturally "wears off" in an asteroid field so the chunks stay close enough to even collide but magically never clump together, or that 1000 years "in the future" will change what was constant for billions of years.
It only seems arbitrary if you don't bother to think about it.
"Sci-fi" already tells you what's the fictional part of the story: the science/tech, and maybe some fundamental rules around those. Fantasy is where you get to rewrite the basic rules of the universe.
In the span of a few decades we went from no planes to flying at almost Mach 10 in air (X-43) and 600.000km/h in space (Parker probe), and from AM radio to a super-computer in everyone's pocket. So you can bet any person can reasonably imagine that in a few centuries we could be advanced enough to build today's sci-fi. That's because they have a few real anchor points in the history of human civilization or even their own lifetime and an easy assessment of the progress of science between them.
Most people also actually think asteroid belts are that dense. But that's because even basic concepts about gravity aren't immediately apparent from day to day experience. Basic grasp of gravity will never allow you to believe it naturally "wears off" in an asteroid field so the chunks stay close enough to even collide but magically never clump together, or that 1000 years "in the future" will change what was constant for billions of years.
It only seems arbitrary if you don't bother to think about it.
I think what you're saying is right but the explanation is backwards. I think of "science fiction" as being fiction in which the science is held constant--the universe works more or less the same way, but with humanity and their technology exploring a different landscape of the possibility space. So the science is real, not fictional. The plot is fiction.
Of course this assumes we're talking about hard sci-fi, which doesn't include stuff like Star Wars.
Of course this assumes we're talking about hard sci-fi, which doesn't include stuff like Star Wars.
Most hard sci-fi breaks the rules too unless it's strictly near future on earth with no space stuff.
Ramscoops don't actually work, you lose velocity collecting the mass. Everything else is subject to the tyranny of the rocket equation unless we're inventing new physics.
Ramscoops don't actually work, you lose velocity collecting the mass. Everything else is subject to the tyranny of the rocket equation unless we're inventing new physics.
Citation for ramscoops not working? Losing velocity is sometimes the point (it works as a sort of magnetic sail / parachute), but I believe the kinetic energy loss is less than the potential energy represented by using the hydrogen as fusion fuel.
I found a paper when I deepdived after reading "A deepness in the sky" but I couldn't find it just now, sorry.
IIRC, it had to do with taking a velocity hit at like 0.9c and then the best you can do is send that atom out at 0.999c out the back. And also the scoop size was gigantic to get mass in sparse interstellar space.
IIRC, it had to do with taking a velocity hit at like 0.9c and then the best you can do is send that atom out at 0.999c out the back. And also the scoop size was gigantic to get mass in sparse interstellar space.
I feel like most people grasp the decay of gravity because of space, and because the moon doesn’t crash into us, etc.
I would wager it’s because the space involved is incomprehensible. It’s not obvious why rocks being 600k miles apart forms any kind of feature. That’s 24 trips around the circumference of the earth. I had honestly presumed they were closer. Not sci-fi movie close, but maybe a few miles in between?
Space is incomprehensibly large to me.
I would wager it’s because the space involved is incomprehensible. It’s not obvious why rocks being 600k miles apart forms any kind of feature. That’s 24 trips around the circumference of the earth. I had honestly presumed they were closer. Not sci-fi movie close, but maybe a few miles in between?
Space is incomprehensibly large to me.
If they grasp how gravity is "decaying" because things are in orbit then they've failed to understand both orbital mechanics and how gravity drops off at distance.
I think it's less "this asteroid belt is unrealistic," and more "I assumed asteroid belts were dense because that's what it's like in movies."
For a lot of people, they know that super nimble spaceships aren't real, but they may have never thought about asteroid belt density. People often see something in media that seems plausible, and assume that's what it's like in reality, even if the media portrayal was way off. I can guarantee it's happened to you at some point.
For a lot of people, they know that super nimble spaceships aren't real, but they may have never thought about asteroid belt density. People often see something in media that seems plausible, and assume that's what it's like in reality, even if the media portrayal was way off. I can guarantee it's happened to you at some point.
The asteroid belt around Sol might be sparse, but what about other solar systems, other galaxies far far away?
Then gravity would condense it all down into a planet in very short order, geologically speaking.
For an example in our own system, see Saturn's rings.
For an example in our own system, see Saturn's rings.
Geologically speaking, sure. But humans don't live in geological timescales: it seems possible that, if humans could somehow explore other star systems on a regular basis, they might come across some systems where there was a relatively recent collision leaving lots of close-together asteroids that haven't yet had enough time to condense into a new body.
Yes, like Saturn's rings.
If such collisions are common, then yes.
A belt like shown in many movies would become a damn black hole with how dense and large they are. They're not just unlike Sol's, they're completely ridiculous.
To be fair, in at least some movies they only say “asteroids” instead of “asteroid belt”.
The aftermath of a recent collision between large bodies might be attractive to future spacefarers because it could expose the differentiated insides of planetoids in a convenient high-density but accessible form for mining. So it wouldn’t be entirely unrealistic for “future stories” to be playing out in these rich and dense regions instead of the space equivalent of the middle of a barren desert.
A statistically representative locale for a story on Earth would be in the middle of an ocean, but that’s not where most stories come from.
The aftermath of a recent collision between large bodies might be attractive to future spacefarers because it could expose the differentiated insides of planetoids in a convenient high-density but accessible form for mining. So it wouldn’t be entirely unrealistic for “future stories” to be playing out in these rich and dense regions instead of the space equivalent of the middle of a barren desert.
A statistically representative locale for a story on Earth would be in the middle of an ocean, but that’s not where most stories come from.
True, but that's not what they usually depict on screen. We see lots of "normal looking", i.e. rounded, well-aged, thoroughly cratered asteroids, neither the fresh shards or glowing/molten material we would expect from a collision.
I do like the idea of prospectors diving into the debris of a recent asteroid collision to gather halfway pre-refined resources. With the rarity of asteroid collisions relative to human lifespans, I imagine the response the way deep sea creatures respond to a whale fall, sudden massive availability of resources. I might try to write that someday.
I do like the idea of prospectors diving into the debris of a recent asteroid collision to gather halfway pre-refined resources. With the rarity of asteroid collisions relative to human lifespans, I imagine the response the way deep sea creatures respond to a whale fall, sudden massive availability of resources. I might try to write that someday.
> neither the fresh shards or glowing/molten material we would expect from a collision.
That's also an undesirable "area" of space for mining. A too-recent collision would be a dangerous area because of the excessive density. A "just right" area for mining might be a hundred thousands years old, but not tens of millions or older.
The terran analogy would be a volcano: Too soon and you're still ankle-deep in lava. Some decades later you have the most fertile land on the planet for your crops. A billion years later it's no different to any other part of the planet and not especially productive.
> whale fall
That's precisely what I was thinking of!
> I might try to write that someday.
I'd read that story! It's a ripe context for drama: the luck of discovery, the gold rush, the fight over the territory by rival groups, the "frontier" aspects and lack of civilized law and order, etc...
That's also an undesirable "area" of space for mining. A too-recent collision would be a dangerous area because of the excessive density. A "just right" area for mining might be a hundred thousands years old, but not tens of millions or older.
The terran analogy would be a volcano: Too soon and you're still ankle-deep in lava. Some decades later you have the most fertile land on the planet for your crops. A billion years later it's no different to any other part of the planet and not especially productive.
> whale fall
That's precisely what I was thinking of!
> I might try to write that someday.
I'd read that story! It's a ripe context for drama: the luck of discovery, the gold rush, the fight over the territory by rival groups, the "frontier" aspects and lack of civilized law and order, etc...
>A too-recent collision would be a dangerous area because of the excessive density.
This doesn't seem like it should be a problem. The space miners don't need to jump straight to the middle of the debris field; they can just start at the very edges. The density of the debris field won't be uniform; it'll be spread out, even shortly after the collision. They can just go to the less-dense areas at the periphery, where it's safer.
This doesn't seem like it should be a problem. The space miners don't need to jump straight to the middle of the debris field; they can just start at the very edges. The density of the debris field won't be uniform; it'll be spread out, even shortly after the collision. They can just go to the less-dense areas at the periphery, where it's safer.
I have a lot of story ideas, but I'll put that one on the list!
If the density of the asteroid belt is too high, I guess it (slowly) collapses and you get a planet.
You should ask them.
> but the ability to fly a space craft with the agility of a fighter jet on Earth is okay?
What makes you think that GP thinks that? The mere fact that they didn't mention that, among all extant silliness in scifi media, in the context of a discussion about asteroids?
What makes you think that GP thinks that? The mere fact that they didn't mention that, among all extant silliness in scifi media, in the context of a discussion about asteroids?
because they said "where it looks like they're flying their spaceships through a raging river of rocks dodging one every second.
The asteroid belt isn't like in Star Wars/Trek. The distances are huge. Average distance, from a quick Google says about 1 million kilometers apart.
true but 40M years is a very long time
Not with those kind of distances. They really shouldn't hit each other ever. Think of two grains of rice in a pot of water. Stir and and see how long it takes for them to touch.
We can't tell how many other collisions there were in belt from looking at the debris that intersect Earth. There were likely lots more that didn't kick debris our direction.
Any sufficiently energetic collision would produce a population of fragments that intersect the orbit of our planet.
The op headline is also using meteorite, which by definition is a rock which reaches the surface of the earth.
The op headline is also using meteorite, which by definition is a rock which reaches the surface of the earth.
Does that mean the asteroid belt is some kind of ancient Kessler Syndrome but for the solar system?
40Mya isn't ancient by solar system standards.
But there was a really big one 66 million years ago that wiped out the dinosaurs. Did that have a similar origin?
"There is broad consensus that the Chicxulub impactor was a C-type asteroid with a carbonaceous chondrite-like composition, rather than a comet.[29][67] These types of asteroids originally formed in the outer Solar System, beyond the orbit of Jupiter."