The cosmic microwave background gives us a view of the universe when it was
A) 14 billion years old.
B) 3-5 minutes old.
C) 380,000 years old.
D) about 1 million years old.

Question

Quizplus · Accepted Answer

The cosmic microwave background gives us a view of the universe when it was 380,000 years old. This is because at that time, the universe had cooled enough for hydrogen atoms to form, and the radiation from this era has been stretched and cooled over time to become the cosmic microwave background radiation that we can observe today.

The Cosmic Microwave Background Gives Us a View of the Universe