How old is the universe and Earth, and what scientific evidence supports these age estimates"?

Well honey, the universe is believed to be about 13.8 billion years old, give or take a few million. Earth is a cute little youngster compared to that, only about 4.5 billion years old. Scientists gathered evidence supporting these ages from a variety of sources, like cosmic background radiation for the universe's age and radioactive dating for Earth's age. These dates are as solid as a Betty White clapback, so don't you worry.