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Hell Plain, walled plain on the Moon

Walled plain on the Moon

A wide lowland region in the Moon's southern hemisphere, lying somewhat to the north of the prominent crater Tycho within a densely cratered region of the Moon's surface. Historically, this region was considered a plain rather than a crater formation, and at that time was commonly known as Hell Plain (for the crater Hell in is southwestern quadrant, itself named after the Hungarian astronomer Maximilian Hell). The region was later recognised as a walled plain, albeit one showing extreme erosion and heavy internal cratering.

The walls of this plain are often indistinct, and hence estimates of its diameter vary considerably, from 227km to 256km, depending on the source. The higher value would make Deslandres the second largest crater formation on the Moon, exceeded only by a similarly structured formation named Bailly, which lies to the southwest. The floor of the plain descends some 1.6km below the surrounding surface, and contains numerous craters. One of these, a satellite crater of Hell named Hell Q, has an extremely reflective floor, and is one of the brightest points on the Moon's surface. Deslandres' walls are broken in several places by further craters, notably Hell and the larger Lexell, each of which obscure parts of the southern walls of the plain.


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