Alright, let's have a look, Sirius is supposedly located 8.6 lightyears away from the Earth. The 10,000 ly bar above is 60 pixels wide, meaning that every pixel covers ~167 lightyears. Oh. It seems like we share a pixel with Sirius. Uhm, let's zoom in.
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Here we have our interstellar neighborhood mapped out in 3D space. It isn't really properly to scale - Tau Ceti is actually further away from us than Sirius is, for example - but it sure gives us an idea of what we actually have around us. All of these stars may be less than a pixel of the Milky Way, but these would be the easiest ones to reach if we tried.
Hmm, have you heard of the Heart Nebula and the Soul Nebula? Those are two absolutely gorgeous nebulae. Here, let me show you a picture of the Heart nebula:
These two nebulae are approximately 7,000 lightyears away from us. I happen to know that these two nebulae lie between us and the central disk of the Milky Way, but the galactic center lies at least 25,000 lightyears away from the Sun, so you wouldn't even be halfway there if you'd reach these bodies.
The Milky Way has a lot of stuff in it, but what can we find outside of the Milky Way? Well, there are other galaxies, but the only one I can think of it the Andromeda Galaxy. Where exact does that lie? Well, I'm glad you asked! The Andromeda Galaxy is actually the largest galaxy in the Local Group:
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What is the Local Group, you ask? Well, it the largest group of bodies that are pulled towards eachother by gravity faster than they are pulled away from one another by the expansion of the universe. This is why the Andromeda Galaxy and the Milky Way will eventually collide. All of the galaxies in the map above, save for some of the galaxies in the upper-left corner (NGC 3109 doesn't like us), are moving towards eachother. In 3.75 billion years, NASA believes the Earth sky will look like this:
The band on the right is the Milky Way, which you may not be used to seeing because of all the light polussion we're dealing with. The galaxy on the left? Andromeda.
But wait, let's go back to the map again. What other galaxies do we have in the Local Group? The third biggest galaxy seems to be the Triangulum Galaxy. Though it doesn't look like much, it should contain about 40 billion stars. Why didn't I find out about the third-biggest galaxy in our Local Group until this week?
If we look a lot closer to our own galaxy, we find the fourth-largest galaxy in our Local Group: the Large Magellanic Cloud (LMC if you want to sound cool). If humanity would ever go to another galaxy, this one would probably be a good pick, seeing its size and proximity. It's only ~163,000 lightyears away from us, after all. If we were able to travel at light speed, the ship's crew would probably evolve into a different species from those who stay on Earth before they'd arrive.
Ahem, intergalactic travel would be a bit extreme, but at least it's nice to know who your neighbors are. To close this off, I want to just show another picture of the Heart Nebula~
Say... what are those bright stars just to the left of the nebula? Hmm, two of them seem to be the Maffei Galaxies: Maffei 1 and Maffei 2. These two galaxies aren't in our local group, and were actually really hard to find. The IC 342/Maffei Group is a neighboring galaxy-group to our Local Group, though the exact distance is hard to tell. The group is kinda hiding behind the Milky Way, in what we call the Zone of Avoidance. To quote Wikipedia: "The Zone of Avoidance (ZOA) is the area of the sky that is obscured by the Milky Way."It's rather annoying, because other groups in the Virgo Supercluster that are farther away from us, like the Sculptor Group, are more easily studied.
Still though, all these groups are way too far away from us. No matter what we do, humanity will never be able to reach these galaxies. I like to imagine what the Local Group would look like from Maffei 2, but because of that dang expansion of the universe, we will never know.
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