Vavilov is a prominent impact crater that is located to the west of the walled plain Hertzsprung. It is located on the far side and cannot be viewed directly from the Earth. About a crater diameter to the northwest is the smaller Chaucer, and farther to the southwest is Sechenov. This is a young impact that still retains the faint remnants of a ray system. (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.