how we can see a star billions of light year away and nothing in between hiding it?
In: Planetary Science
Space is largely empty and most stars are clumped together in the form of galaxies and super clusters.
Space is mostly empty space.
The universe is mostly nothing with a few small bits of matter here and there.
We also only see the parts that we can see because there is nothing blocking the view.
It is like standing in a forest and seeing trees everywhere. Some of the trees might be quite far away and you would be surprised that you can see them with nothing blocking the view, but that doesn’t mean that there aren’t other trees that you can’t see in the forest. (Just that the universe is a very, very thin forest with a few copse of trees in a whole lot of empty fields.)
Also the farthest star you can see with the naked eye is only a few thousand light years away instead of a billions of light years.
For looking at things much further away we often use instruments that allow us to look through things like clouds of dust.
Space is, by an extreme margin, mostly empty. Even our solar system is mostly empty, with light years of empty space to the next one system. Dust clouds we see in space can often be light years across, and still look like nothing when you’re inside it.
Depictions of space in media and diagrams do not do justice to the scale everything is, how completely massive they are, and how tiny they are yet in comparison to the space in between them.
Space is big. Really big, I mean, you might think it’s a long way down the road to the chemist, but that’s just peanuts to space. (Douglas Adams).
Space is empty. Really empty. I mean, you might think that all those big planets, stars, and asteroid belts out there would be bumping up against each other all the time, but it’s 99% (figure pulled out of my arse) empty and everything is really l, *really* far away from everything else. (Me).
Will also point out that a lot of stuff is hidden from us. We can’t, for example, really make much out of what’s behind the core of Milky Way, our home galaxy. Actually, the galactic plane obscures about 20% of the galactic sky.
If we’re not talking supernova, then we can only see stuff into the thousands in flight years away.
When it comes to billions, we’re talking about a wide range of extremely sensitive detectors.
1. There’s a colossal amount of approximately nothing between us and them
2. _Stuff_ is transparent to some wavelengths
3. It was much closer when it emitted what we’re seeing
4. What we see from billions of light years away isn’t little red dwarfs, its entire galaxies worth of stars all emitting with just enough photons reaching us to resolve, and only if we look at the same precise spot for a long time
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