Moonwatch
“Lansberg is well preserved for its age, its rim sharp all the way around”
Lansberg is a sharply-defined, 40km-diameter crater located on the Mare Insularum, in a region of the lunar surface bordering the Oceanus Procellarum and the Mare Nubium, with the Mare Cognitum to the south. The best way to find Lansberg is via the impressive ray crater Copernicus (93km wide). Starting at Copernicus, head south, straying slightly west until you arrive at crater Reinhold (48km). Follow the line from Copernicus through Reinhold for about two-thirds that distance again, veering slightly to the west. This should take you directly to Lansberg.
Lansberg is remarkably well preserved for its age, its rim sharp and continuous all the way around. The inside of the crater wall shows some good terracing, and the highest point of rim towers 3km over the flat floor below. The western edge is the lowest, rising to around 2.1km. The crater’s floor is flat with a double peak in the centre.
The area surrounding Lansberg is lava filled, fairly flat and dark. Several strips of lighter material ejected from the impact that formed Copernicus can also be seen. A number of small but prominent craters lie west and southwest of Lansberg. These are notable because of their varied appearance. Several show bright petal-like ejecta patterns, notably Lansberg A (9km), B (10km), D (10km) and E (6km). Lansberg C (20km), F (9km) and G (10km) appear as ring formations, their interiors having been flooded by lava.
Of particular interest is Lansberg G, or rather the region immediately to the west of this crater. Here you’ll find a small feature often depicted on charts as a tiny 5km crater labelled Lansberg GA, with a rim that touches Lansberg G. However, the feature is complex and irregular in shape, appearing less like a true crater when viewed
at high magnification. An 8-inch or larger telescope should start to give a decent view of this curious region.
Lansberg D is an interesting feature too, well worth investigating when the sunrise terminator lies just to the west – approximately three days after first quarter. Positioned to the southeast of the main crater are three prominent lunar domes that stand out very well when the illumination is oblique. Two of the domes are elliptical in shape measuring 18-20km across. The third is more triangular in shape, apparently connected to the southeast edge of the more southerly elliptical dome.
When the illumination is low, it is possible to see numerous wrinkle ridges in the surrounding lava, regions where the surface of the Moon has buckled and cracked as the lava has cooled. A notable ridge runs south from Lansberg G, immediately west of Lansberg E and F. Another can be seen passing west-east south of the Lansberg D domes mentioned above.
While in the region, it’s also worth checking out the huge, partial crater Euclides P. At 66km in diameter it is notably larger than Lansberg and significantly larger than its primary, the 12km ray crater Euclides, located farther to the south-southwest. Euclides P shows a semicircular southern rim which gets lost in the lava towards the north. Interestingly, the crater still manages to retain its elliptical form thanks to rough terrain to the north, the southern edge of which arcs around to hint at the outline of the original crater.