Janssen (Moon)

Named after Pierre Jules César Janssen - French astronomer (1824-1907).

Janssen Crater is an impact crater in the Arabia quadrangle on Mars at 2.7° N and 322.5° W. and is 158.0 km in diameter. A picture below show these layers, as well as dark slope streaks. The darker the streak, the younger it is. (wikipedia entry)

A crater is a circular depression likely created by an impact event. On the Moon they are named after deceased scientists, polar explorers, astronauts or cosmonauts.