Question

What event do astronomers think “cosmic background radiation” is left over from?

Answer 1

left over from the big bang.

Explanation:

At the time of Big Bang the temeperture was very very high,..AS u inverse expanded it cooled down and after 13,.82 billion years ti is still there 2.7 degree Kelvin/.This relic of Big bang is the cosmic micro wave bck ground radiation.