Runge 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...

 in the 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...

, along the eastern edge 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...

. It lies less than one crater diameter to the north-northwest of the very similar crater Warner

Warner (crater)

Warner is a lunar crater that is located in the southern part of the Mare Smythii, near the eastern limb of the Moon. In this location the crater is viewed almost from the edge from Earth, and is sometimes hidden from sight due to libration. The crater lies just to the south-southeast of the very...

. To the west-northwest is Haldane

Haldane (lunar crater)

Haldane is a lunar crater that is located in Mare Smythii, near the eastern limb of the Moon. The visibility of this formation is affected by libration, and even under favorable conditions it is highly foreshortened...

. Runge has been almost completely submerged by basalt

Basalt

Basalt is a common extrusive volcanic rock. It is usually grey to black and fine-grained due to rapid cooling of lava at the surface of a planet. It may be porphyritic containing larger crystals in a fine matrix, or vesicular, or frothy scoria. Unweathered basalt is black or grey...

ic 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, ring-shaped feature in 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...

. The rim has a gap at the southern end, and a pair of small craters lie near the exterior to either side of this opening.