When the microwave background radiation was emitted, about how big was the universe?
A)smaller than the head of a pin
B)1/1,000,000 its current size
C)1/100,000 its current size
D)1/1,000 its currents size
E)1/100 its current size

Question

Quizplus · Accepted Answer

The cosmic microwave background radiation was emitted about 380,000 years after the Big Bang when the universe was about 1/1,000 its current size. This corresponds to a size of about 30 million light years in diameter, which is still quite large. Therefore, the best choice is D, 1/1,000 its current size.

When the Microwave Background Radiation Was Emitted, About How Big