240px, Location of the crater Challis Challis is a

lunar Lunar most commonly means "of or relating to the Moon". Lunar may also refer to: Arts and entertainment * ''Lunar'' (series), a series of video games * "Lunar" (song), by David Guetta * "Lunar", a song by Priestess from the 2009 album ''Prior t ...

impact crater An impact crater is a circular depression in the surface of a solid astronomical object formed by the hypervelocity impact of a smaller object. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters ...

that is located in the northern regions of the

Moon The Moon is Earth's only natural satellite. It is the fifth largest satellite in the Solar System and the largest and most massive relative to its parent planet, with a diameter about one-quarter that of Earth (comparable to the width of ...

's near side, close enough to the limb to appear significantly foreshortened when viewed from the

Earth Earth is the third planet from the Sun and the only astronomical object known to harbor life. While large volumes of water can be found throughout the Solar System, only Earth sustains liquid surface water. About 71% of Earth's surfa ...

. It is joined to the crater

Main Main may refer to: Geography * Main River (disambiguation) **Most commonly the Main (river) in Germany * Main, Iran, a village in Fars Province *"Spanish Main", the Caribbean coasts of mainland Spanish territories in the 16th and 17th centuries ...

through a break in the northern rim, and is close to

Scoresby Scoresby may refer to: People * William Scoresby (1789–1857), British Arctic explorer, scientist and clergyman * William F. Scoresby (1840–1884), New York politician * William Scoresby Routledge (1859–1939), British ethnographer, anthropolo ...

along the southeast side. The rim of this crater has been damaged and eroded by a history of impacts, with the most intact portion located along the southeastern half. A small crater lies across the southern rim, and the remaining rim is notched and irregular. The interior floor of both Challis and Main have been resurfaced forming a relatively level bottom common to both formations. This surface is marked only by multiple tiny craterlets.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Challis.

References

* * * * * * * * * * * * Impact craters on the Moon {{Craters on the Moon: C-F