If you were a passenger on a merry-go-round, would you be able to work out your position based on the movement or location of the other riders? Or when you look around and see other people on a different ride or a ferris wheel?
Your brain can calculate distance because of the parallax that you get from having two eyes. Or you can see that people look smaller when they are further away (assuming you are familiar with the average size of a person). You can also hear sounds change pitch as you move towards or away from them.
Imagine these same principles applying to different positions in orbit around the Sun throughout the year, type 1A supernovae, and red / blue shift of light, and you can begin to map images of stars and galaxies pretty well.
We can see that we are in a spiral shaped galaxy, and that we are not in a globular galaxy. Our spiral galaxy has arms with varying density, and we can also determine that we are in an area that is relatively less dense, meaning that we are between arms. We also can look towards the center of our galaxy and measure our distance from the middle
IAmAPhysicsGuy t1_j4jydnx wrote
Reply to How do we know that we are in a certain place inside our galaxy? and how do we know how big it is just by looking at the cross section we are in? by friday_panda
If you were a passenger on a merry-go-round, would you be able to work out your position based on the movement or location of the other riders? Or when you look around and see other people on a different ride or a ferris wheel?
Your brain can calculate distance because of the parallax that you get from having two eyes. Or you can see that people look smaller when they are further away (assuming you are familiar with the average size of a person). You can also hear sounds change pitch as you move towards or away from them.
Imagine these same principles applying to different positions in orbit around the Sun throughout the year, type 1A supernovae, and red / blue shift of light, and you can begin to map images of stars and galaxies pretty well.
We can see that we are in a spiral shaped galaxy, and that we are not in a globular galaxy. Our spiral galaxy has arms with varying density, and we can also determine that we are in an area that is relatively less dense, meaning that we are between arms. We also can look towards the center of our galaxy and measure our distance from the middle