Answer:
Red shift
Explanation:
In 1929, it was observed by Edwin Hubble through the Hubble telescope that the galaxies are moving away from each other. He reached this conclusion by analyzing the red shift. This means that galaxies which are far away have faced maximum redshift. It bears a similarity with the big bang theory.
According to big bang theory, the universe originated from a huge explosions after which every thing is just moving away from each other.
