Are there more stars now?
July 25, 2022 7:41 AM Subscribe
I know the James Webb Space Telescope has made many more galaxies and stars visible to us. What I don't know is: has what we've seen so far changed the estimate of the number of stars in the universe? In other words, do scientists now think there are actually more stars out there than previously anticipated?
Best answer: The Webb telescope will probably make more things visible, but it's only been operational for a few days, and it hasn't had time to revolutionize things.
The last estimate I heard of the number of stars was 200 billion galaxies, each with 200 billion stars. This was updated three or four years ago to 400 billion galaxies, pre-Webb. I don't know if that's widely accepted.
The problem with any estimate is that it's almost impossible to do. You can't possibly count all the galaxies, because some are behind others, behind dust clouds, or too far away. It's the same with stars - if a galaxy shows up as a point of light, you guess. If you're in one, you look at the sky and guess. The stars are too close together, they overlap other stuff, and there are just too many of them. Count one a second and you're set for maybe fifteen thousand years.
Also Galaxies come in different types, and I'm not sure we have a really good idea of how many stars each type contains.
A few years back a group of astronomers suggested that, since the universe is generally thought to curve space, light fired in one direction might be coming back the other way. This would mean that the distant galaxies we see are actually the backs of ones closer to us. The guy in charge was asked what the minimum number of galaxies could be, and he said, "Four."
This is fairly ridiculous, probably, but so is any hard estimate.
We often see estimates of the number of people watching a parade. You measure a twenty foot square, try to count all the people in it from a photo, estimate the number of twenty foot squares along the route, assume the density is the same, and come up with a number. This is presented as a fact, and it's probably not off by more than a factor of ten in either direction.
Stars are the same, but much worse. I'd be completely unsurprised if we were off by ten times or a tenth, so 400 billion squared, but maybe 4000 billion squared, but maybe 40 billion squared, or, given that ridiculous one, 4 times 20 billion or 200 billion or 4000 billion.
But I wouldn't be too staggered if it was 100x or 0.01x.
And then there's the steady state theory, which says that we're a small expanding bubble in an infinitely large universe which has no beginning or end either in time or space.
I don't think this question can be really answered. Webb hasn't changed this, but it most likely will, depending on how it's used and how long it lasts.
posted by AugustusCrunch at 1:07 PM on July 25, 2022 [1 favorite]
The last estimate I heard of the number of stars was 200 billion galaxies, each with 200 billion stars. This was updated three or four years ago to 400 billion galaxies, pre-Webb. I don't know if that's widely accepted.
The problem with any estimate is that it's almost impossible to do. You can't possibly count all the galaxies, because some are behind others, behind dust clouds, or too far away. It's the same with stars - if a galaxy shows up as a point of light, you guess. If you're in one, you look at the sky and guess. The stars are too close together, they overlap other stuff, and there are just too many of them. Count one a second and you're set for maybe fifteen thousand years.
Also Galaxies come in different types, and I'm not sure we have a really good idea of how many stars each type contains.
A few years back a group of astronomers suggested that, since the universe is generally thought to curve space, light fired in one direction might be coming back the other way. This would mean that the distant galaxies we see are actually the backs of ones closer to us. The guy in charge was asked what the minimum number of galaxies could be, and he said, "Four."
This is fairly ridiculous, probably, but so is any hard estimate.
We often see estimates of the number of people watching a parade. You measure a twenty foot square, try to count all the people in it from a photo, estimate the number of twenty foot squares along the route, assume the density is the same, and come up with a number. This is presented as a fact, and it's probably not off by more than a factor of ten in either direction.
Stars are the same, but much worse. I'd be completely unsurprised if we were off by ten times or a tenth, so 400 billion squared, but maybe 4000 billion squared, but maybe 40 billion squared, or, given that ridiculous one, 4 times 20 billion or 200 billion or 4000 billion.
But I wouldn't be too staggered if it was 100x or 0.01x.
And then there's the steady state theory, which says that we're a small expanding bubble in an infinitely large universe which has no beginning or end either in time or space.
I don't think this question can be really answered. Webb hasn't changed this, but it most likely will, depending on how it's used and how long it lasts.
posted by AugustusCrunch at 1:07 PM on July 25, 2022 [1 favorite]
An over abundance or unexpected dearth of stars would have made the news, so it’s fair to say that no big changes have been found.
posted by Tell Me No Lies at 5:27 PM on July 25, 2022
posted by Tell Me No Lies at 5:27 PM on July 25, 2022
We can estimate the number of stars in the galaxies around us, but we can't estimate the number of stars in the whole universe because we don't know how big the universe actually is. The early universe expanded monstrously fast, way faster than the speed of light, so much of the universe is just too far away for us to see and, thanks to the universe expanding, it's getting farther away all the time. The light from the farthest stars will never reach us! It's like you're stuck in one room of a house, and reason there must be other rooms, but you can't see them for yourself.
The James Webb telescope lets us see farther away than, for example, the Hubble. And the farther away we can see, the farther back in time we see (since some star's light take billions of years to reach us). The new data might eventually help give us an idea how fast the early universe inflated and even what shape the universe is, which would answer the question about the total number of stars, but that's far down the road.
posted by jabah at 5:38 PM on July 25, 2022 [1 favorite]
The James Webb telescope lets us see farther away than, for example, the Hubble. And the farther away we can see, the farther back in time we see (since some star's light take billions of years to reach us). The new data might eventually help give us an idea how fast the early universe inflated and even what shape the universe is, which would answer the question about the total number of stars, but that's far down the road.
posted by jabah at 5:38 PM on July 25, 2022 [1 favorite]
« Older Fashion related events in the Seattle? | How do I find my fantasy European village rental... Newer »
This thread is closed to new comments.
There may be 2 trillion galaxies in the observable universe,[7][8] although that number was reduced in 2021 to only several hundred billion based on data from New Horizons.[9][10]
I am not aware of any new estimates based on JWST, and a cursory search did not turn any up.
posted by SaltySalticid at 9:04 AM on July 25, 2022