8.8 Billion
One billion dollars. exploring the first billion dollar ico Billion astrobiology How old are galaxies?
How Much Do You Actually Know About Astronomy?
How much do you actually know about astronomy? Astronomy correct Nasa old galaxies age universe years billion earth milky way sun kids caltech jpl credit
World population hits 7 billion
Looking back 3.8 billion years into the root of the “tree of life .
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