1. What observations show that the universe is expanding?

Question

2. What can astronomers infer from the fact that other galaxies are moving away from ours?

Please help!
Thanks :)

Answer 1

doesn't those two questions answer each other?

1. What observations show that the universe is expanding?
the galaxies are moving away.

2. What can astronomers infer from the fact that other galaxies are moving away from ours?
the galaxy is expanding.

Answer 2

The Doppler shift gives us information about whether objects are moving toward us or away from us.

I searched Google under the key words "universe Doppler" to get these possible sources:

http://imagine.gsfc.nasa.gov/YBA/cyg-X1-mass/Doppler.html
http://www.pbs.org/wgbh/nova/universe/moving.html
http://www.exploratorium.edu/hubble/tools/doppler.html
http://www.dmns.org/main/minisites/spaceodyssey/teachersGuide/grades912/pdf/expansionUniverse.pdf

I hope this helps. Thanks for asking.