Ask Ethan #110: What Did The Sky Look Like When Earth First Formed?

Ask Ethan #110: What did the sky look like when Earth first formed?

“In general, what would the night time skies have looked like to an observer on a newly cooling Earth 4 billion years ago? Would the night sky be the same? Brighter?”

The night sky is a memorable, inimitable sight. With the exception of the planets, the stars that shine so brightly and consistently on your birthday will be the same ones — in both position and brightness — that shine on your dying day. But as recognizable as the stars and constellations are, the skies we recognize would have nothing in common with the skies as they were back when Earth first formed more than four billion years ago. With natural light pollution from volcanism and heat, a location inside a star cluster and the evolution of our local Universe, there are some huge differences that would make for some big surprises.