How can we tell if the universe is expanding?

1 Answer
chandramohanPanakkal
Sep 16, 2017

Astronomers study the spectrum of distant galaxies and find the red shift.

Explanation:

The Doppler effect is used to find the red shift..When a galaxy is moving away from us the light waves get elongated The far way galaxies are moving faster than near ones. obeying Hubble law..enter image source here
perfect astronomy.com. picture.

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