Gum 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 near the southeastern 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...

, and is viewed nearly from the side from Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

. It lies along the western edge of the irregular Mare Australe

Mare Australe

Mare Australe is a lunar mare located in the southeastern hemisphere of the Moon. It is 603 kilometers in diameter, overlapping the near and far sides of the Moon. Smooth, dark volcanic basalt lines the bottom of the mare...

, to the northeast of the crater Hamilton

Hamilton (crater)

Hamilton is a lunar impact crater that is located near the southeastern limb of the Moon. From the Earth this crater is viewed nearly from the edge, limiting the amount of detail that can be observed...

. To the north-northwest is the larger Abel

Abel (crater)

Abel is an ancient lunar crater that lies near the southeast limb of the Moon's near side. It is located to the south of the crater Barnard, at the northwest edge of the Mare Australe....

, and to the east-southeast on the far side of the Moon is Jenner

Jenner (crater)

Jenner is a lunar crater that is located within the Mare Australe. It lies just past the southeastern limb, on the far side of the Moon, and can be viewed from the Earth during periods of favorable libration and lighting...

.

The interior floor of this crater has been completely resurfaced 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...

 that has entered through a break in the eastern rim. The surviving rim forms a shallow, arcing ridge about the interior. A small flooded crater lies across the southeast rim, and the remains of a small crater form an incision along the northeastern rim. The interior floor has the same low albedo

Albedo

Albedo , or reflection coefficient, is the diffuse reflectivity or reflecting power of a surface. It is defined as the ratio of reflected radiation from the surface to incident radiation upon it...

 as 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...

to the east, and is marked only by a few small craterlets.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater mid-point that is closest to Gum.

Gum	Latitude	Longitude	Diameter
S	39.8° S	85.0° E	33 km