I’ve always wondered how astronomers can actually observe galaxies that are millions or even billions of light-years away. What exactly are we seeing when we look at them?
And when scientists say there are hundreds of billions, or possibly trillions, of galaxies in the observable universe, how do they know that if we obviously haven’t seen and counted every single one?
Just so you know, you don’t need special equipment to see another galaxy. If you have good eyes, you can just go to a very dark place and look up. A pair of binoculars definitely helps though.
https://en.wikipedia.org/wiki/Andromeda_Galaxy
There’s actually a bunch of local galaxies that you can see with just a pair of binoculars, a small telescope, or a good camera and some time.
The Messier Objects are one catalog of things that are pretty bright in the sky that you can see with your eyeballs through any basic telescope or binoculars. The numbers don’t really mean anything, they’re just the order they were cataloged in.
https://en.wikipedia.org/wiki/Messier_object
If you check out the list, you can see that a lot of them are galaxies. If you spend a little time learning how to find them, you can see them yourself. – Andromeda is M32.
Those are all part of the Local Group. Which are a bunch of galaxies that are all nearby and pretty easy to find with telescopes.
https://en.wikipedia.org/wiki/Local_Group