What optical device is the Dutch scientist, after whom the lunar crater Jansen is named, credited for?
Jansen (crater) Jansen is a lunar crater in the north part of the Mare Tranquillitatis, named after Zacharias Janssen. It is located to the east-southeast of the crater Plinius. The rim of Jansen is low and narrow, with a notch along the western edge. The interior is relatively level, which may indicate it has been covered by lava. To the south-southwest a small but prominent crater lies on the crater floor, halfway between the center and the rim, further southeast is a small but prominent crater named Sinas.
Kundt (crater) Kundt is a small, bowl-shaped lunar impact crater in the northern section of the Mare Nubium, and is named after the German physicist August Kundt. It has a raised rim and is not significantly worn due to impact erosion. This crater lies part way between Guericke to the west and Davy in the east.