Haldane (lunar crater)
Encyclopedia
Haldane is a lunar
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

 crater
Impact crater
In the broadest sense, the term impact crater can be applied to any depression, natural or manmade, resulting from the high velocity impact of a projectile with a larger body...

 that is located in Mare Smythii
Mare Smythii
Mare Smythii is a lunar mare located along the equator on the easternmost edge of the lunar near side. The Smythii basin where the mare is located is of the Pre-Nectarian epoch, while the surrounding features are of the Nectarian system...

, near the eastern limb of the Moon
Moon
The Moon is Earth's only known natural satellite,There are a number of near-Earth asteroids including 3753 Cruithne that are co-orbital with Earth: their orbits bring them close to Earth for periods of time but then alter in the long term . These are quasi-satellites and not true moons. For more...

. The visibility of this formation is affected by libration
Libration
In astronomy, libration is an oscillating motion of orbiting bodies relative to each other, notably including the motion of the Moon relative to Earth, or of Trojan asteroids relative to planets.-Lunar libration:...

, and even under favorable conditions it is highly foreshortened. It lies just to the west-northwest of the crater Runge
Runge (crater)
Runge is a lunar crater in the Mare Smythii, along the eastern edge of the Moon. It lies less than one crater diameter to the north-northwest of the very similar crater Warner. To the west-northwest is Haldane. Runge has been almost completely submerged by basaltic lava, leaving only a low,...

, and to the east of Carrillo
Carrillo (crater)
Carrillo is a small lunar crater located near the eastern limb of the Moon. In this location the crater is subject to lunar libration effects, and appears highly oval due to foreshortening. The rim of this crater is roughly circular, with an inner wall that is wider on the western side than to the...

.

The interior of this floor has been flooded by lava
Lava
Lava refers both to molten rock expelled by a volcano during an eruption and the resulting rock after solidification and cooling. This molten rock is formed in the interior of some planets, including Earth, and some of their satellites. When first erupted from a volcanic vent, lava is a liquid at...

, leaving only a low rim projecting up through the lunar mare
Lunar mare
The lunar maria are large, dark, basaltic plains on Earth's Moon, formed by ancient volcanic eruptions. They were dubbed maria, Latin for "seas", by early astronomers who mistook them for actual seas. They are less reflective than the "highlands" as a result of their iron-rich compositions, and...

. This rim is broken along the northwest face, leaving a gap into the interior. In the eastern half of the inner floor is a semi-circular feature that is concentric with the outer wall. There is also a low central ridge offset to the east of the interior mid-point.
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