Does mass change as you move around the universe?

What is created when solids,liquids,an gases mix with one another

Light from the sun reaches the earth in 8.3 minutes. the velocity is 3.00 x 10^8 m/s. how far is earth from the sun? i know how to get to d = (3 x 10^8 m/s)(498 sec). i just don't know how to get from there to the answer being 1.5 x 10^11 m.

4. if you were an astronaut on the moon, what would you experience? what would you see from your perspective?