Basically, Astrophysics is the study of how the universe works and the things in it like planets, nebulas, and other things like that.
Cosmology is the study of the universe as a whole.
This really isn't a lab, but a little informational section about the universe and stuff. Astronomical distance is the process in measuring distance stars are away from earth by their luminesence. Assuming all stars have the same brightness, brighter stars would be closer and dimmer stars would be further away. Stars of the same brightness would be at the same distance. Parallax is another way to determine the distance of stars.