Jansen is a lunar crater that was named after what Dutch spectacle-maker from Middleburg?
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.
Fabricius (crater) Fabricius is a lunar impact crater that is located within the northeast part of the walled plain Janssen.. At this location, from Earth, the crater appears oval due to foreshortening, but the crater is actually nearly circular. Attached to the north-northwest rim is the slightly larger cater Metius. Fabricius has multiple central peaks that rise to 0.8 km, with a rugged rise to the northwest running north–south. The rim is lumpy and somewhat distended, most noticeably to the southwest and south. It is 78 kilometers in diameter and 2,500 meters deep. It is from the Eratosthenian period, 3.2 to 1.1 billion years ago. It is named after David Fabricius, a 16th-century German astronomer.