Not the best picture of the Moon last night but the Tycho crater was very prominent. It has a very clear ray system spreading out. I could see clearly several other nearby craters silhouetted against the dark edge of the Moon.
This suggests that these could be some of the ones formed when large lumps ejected by the impact came back down close by. It says that Tycho is a reasonably recent crater. If the impact had been visible from Earth, it would have been when yesterday's Purbeck Marble was still living snails!
