How do astronomers know the universe is still expanding instead of rotating towards a central high density object?
1 Answer
Feb 4, 2017
Red shifts in spectra's. This is the stellar Doppler effect.
Explanation:
A red shift is how the lines in a objects spectra shift to the right (red). This is the stellar Doppler effect. We witness red shifts in almost all objects, and this means they are moving away from us, expanding the Universe (however that works ;-)
