Alder 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...

 impact 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 the southern hemisphere

Southern Hemisphere

The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...

 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 South Pole-Aitken basin

South Pole-Aitken basin

The South Pole-Aitken basin is an impact crater on Earth's Moon. Roughly in diameter and deep, it is one of the largest known impact craters in the Solar System. It is the largest, oldest and deepest basin recognized on the Moon. This moon basin was named for two features on opposing sides; the...

, and lies to the southeast of the crater Von Kármán

Von Kármán (lunar crater)

Von Kármán is a lunar crater that is located in the southern hemisphere on the far side of the Moon. The northern third of this formation is overlain by the rim and outer rampart of the walled plain Leibnitz, forming a deep indentation in the formation...

. Southeast of Alder is Bose

Bose (crater)

Bose is a lunar impact crater that is located on the far side of the Moon, in the southern hemisphere. It lies just to the northwest of the smaller crater Bhabha, and southeast of Alder....

, and to the south-southwest lies Boyle

Boyle (crater)

Boyle is a lunar impact crater that is located in the southern hemisphere on the rugged far side of the Moon. It is adjacent to the larger crater Hess to the southeast, and lies about mid-way between the craters Alder to the north-northeast and Abbe to the south-southwest.The outer rim of Boyle is...

.

The inner wall of Alder is rough and slightly terraced, with the material scattered across the edges of the otherwise relatively flat interior floor. There are several low central ridges lying along a band from the mid-point toward the eastern rim. A small crater lies on the eastern inner slopes. The crater is otherwise free of significant impacts within the rim.

Alder is associated with the only area in the basin not dominated by the pyroxene

Pyroxene

The pyroxenes are a group of important rock-forming inosilicate minerals found in many igneous and metamorphic rocks. They share a common structure consisting of single chains of silica tetrahedra and they crystallize in the monoclinic and orthorhombic systems...

 rocks typical of lunar lowlands. This alder ejecta area is on spectrograph

Spectrograph

A spectrograph is an instrument that separates an incoming wave into a frequency spectrum. There are several kinds of machines referred to as spectrographs, depending on the precise nature of the waves...

ic evidence instead principally anorthosite

Anorthosite

Anorthosite is a phaneritic, intrusive igneous rock characterized by a predominance of plagioclase feldspar , and a minimal mafic component...

rock, typical of the lunar highlands.

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 Alder.

Alder	Latitude	Longitude	Diameter
E	47.6° S	172.3° W	16 km