2
votes
1answer
50 views

Data for red-shifting

I am looking for basic data regarding red-shifting that comes with reliable measure of distance of the emitting star.
3
votes
2answers
47 views

how does redshift prove expansion is accelerating?

My astronomy teachers never would answer this for me... Redshift obviously indicates an object (such as another galaxy) is moving away, but how do we know its acceleration from this? It's my ...