Ancient Astronomers and Ancient Lunar Impacts

We return to two of our favorite topics, the red giant star Betelgeuse, and of course the Moon. Some clever historical detective work has revealed that Betelgeuse was not red, but yellow, two thousand years ago. This tells us how massive the star is and how far along it is in its evolution to a supernova. Closer to home, another clever bit of detective work gives a new history to ancient lunar craters by examining the Moon's gravitational lumpiness. Cool!