Gernsback 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...

 on the far side 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 is located in the northeastern part of the uneven 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...

, just behind the southeastern limb. During periods of favorable 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:...

 this feature can be brought into view of the 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...

, but it is seen from the side and not much detail can be observed. It is located about a crater diameter north of the larger crater Lamb

Lamb (crater)

Lamb is a lunar crater that lies beyond the southeastern limb on the Moon's far side. It is located in an irregular lunar mare region named Mare Australe, just to the east of the crater Jenner....

, and southwest of Parkhurst

Parkhurst (crater)

Parkhurst is a heavily degraded lunar crater to the northeast of the Mare Australe on the far side of the Moon. To the north-northeast of Parkhurst is the crater Scaliger and to the southwest lies the dark-floored Gernsback. The small lunar mare named Lacus Solitudinis lies due north of...

.

The interior of this crater 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 a level surface with a 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...

 that matches the dark appearance of 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...

region to the south and west. The surviving rim is a slender, circular feature with some erosion along the southeastern edge. A small crater lies across the southern rim.

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 Gernsback.

Gernsback	Latitude	Longitude	Diameter
H	38.2° S	103.5° E	43 km
J	37.7° S	101.9° E	18 km