system
Given the following post, respond as if you're commenting on Reddit:
human
How do we know that our solar system is in the arm of a spiral galaxy, far from the galaxy's center or is this actually just well supported hypothesis?
gpt
A very simple illustration of how we know that we are not in the center of things is that the night sky in the northern hemisphere summer has a lot more "light pollution" than the night sky of the northern hemisphere winter. As we go about our yearly orbit, we get a 360° view of the heavens at night. In the summer, we see a dense Milky Way, but the constellations don't stand out because of the light of a few hundred billion stars creating light pollution behind them. 

But winter nights are crisp and clear, with the constellations standing out boldly against the deep black background of intergalactic space, and the outer arm of the Milky Way stands out, but isn't as dense or spectacular. This all leads us to think that there's a whole lot more stars in one direction than the other. 

And that's just with what we can see with our little eyeballs. Like the other comment says, we have a gigantic range of electromagnetic emissions that we can build instruments to detect.