What Dutchman was born in 1585 and had a lunar crater Jansen named after him?
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.
Cajal (crater) Cajal is a tiny lunar impact crater on the northern part of the Mare Tranquilitatis, in memory of the Spanish doctor and Nobel laureate Santiago Ramón y Cajal. It is a circular, cup-shaped formation that lies about 60 km southeast of the lava-inundated crater Jansen. Cajal was formerly designated Jansen F, prior to renaming by the IAU. Also to the northwest is a system of wrinkle ridges designated the Dorsa Barlow.