Van de Graaff is a crater formation located on the

far side of the Moon The far side of the Moon is the lunar hemisphere that always faces away from Earth, opposite to the Near side of the Moon, near side, because of synchronous rotation in the Moon's orbit. Compared to the near side, the far side's terrain is ru ...

, on the northeast edge of

Mare Ingenii Mare Ingenii (Latin ''ingeniī'', the "Sea of Cleverness") is one of the few lunar mare features on the far side of the Moon. The mare sits in the Ingenii basin, which is of the Pre-Nectarian epoch, which lies in turn in the outer part of the old ...

. The crater is named for physicist Robert J. Van de Graaff, whose groundbreaking work includes the invention of the

Van de Graaff generator A Van de Graaff generator is an electrostatic generator which uses a moving belt to accumulate electric charge on a hollow metal globe on the top of an insulated column, creating very high electric potentials. It produces very high voltage ...

Description

Van de Graaff has the appearance of two merged craters, approximately in a figure-8 shape with no intervening rim separating the two halves. The crater Birkeland is attached to the southeast rim, nestling against the slightly narrower "waist" of the formation. To the north is Aitken, and

Nassau Nassau may refer to: Places Bahamas *Nassau, Bahamas, capital city of the Bahamas, on the island of New Providence Canada *Nassau District, renamed Home District, regional division in Upper Canada from 1788 to 1792 *Nassau Street (Winnipeg), ...

lies to the east. The outer rim has some terracing along the southwest wall, but is generally in a worn and eroded state. A pair of craterlets overlay the southeast rim, next to Birkeland. There are also several small craters on the interior floor of Van de Graaff. The southwest section has a central peak, while the northeast floor is slightly smoother in form. Orbital studies of the Moon have demonstrated that there is a local

magnetic field A magnetic field is a vector field that describes the magnetic influence on moving electric charges, electric currents, and magnetic materials. A moving charge in a magnetic field experiences a force perpendicular to its own velocity and to ...

in the vicinity of this formation that is stronger than the natural lunar field. This is most likely an indication of

volcanic A volcano is a rupture in the crust of a planetary-mass object, such as Earth, that allows hot lava, volcanic ash, and gases to escape from a magma chamber below the surface. On Earth, volcanoes are most often found where tectonic plates a ...

rock underneath the surface. The crater also has a slightly higher concentration of

radioactive Radioactive decay (also known as nuclear decay, radioactivity, radioactive disintegration, or nuclear disintegration) is the process by which an unstable atomic nucleus loses energy by radiation. A material containing unstable nuclei is consi ...

materials than is typical for the lunar surface. The crater walls in the vicinity of Van de Graaff display an unusual grooved texture. This region lies at the antipode of the

Mare Imbrium Mare Imbrium (Latin ''imbrium'', the "Sea of Showers" or "Sea of Rains", "Sea of Tears") is a vast lava plain within the Imbrium Basin on the Moon and is one of the larger craters in the Solar System. The Imbrium Basin formed from the colli ...

impact site, and it is thought that powerful

seismic wave A seismic wave is a wave of acoustic energy that travels through the Earth. It can result from an earthquake, volcanic eruption, magma movement, a large landslide, and a large man-made explosion that produces low-frequency acoustic energy ...

s from this event converged at this point.''Seismic effects from major basin formations on the moon and mercury''. Schultz, P.H. & Gault, D.E. The Moon (1975) 12: 159. https://doi.org/10.1007/BF00577875 Most likely this energy created the grooved appearance as the tremors triggered

landslide Landslides, also known as landslips, are several forms of mass wasting that may include a wide range of ground movements, such as rockfalls, deep-seated grade (slope), slope failures, mudflows, and debris flows. Landslides occur in a variety of ...

s, although the grooves may also have been formed by deposited clumps of ejecta from the impact.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Van de Graaff.

References

External links

Figure 20
in Chapter 2 of APOLLO OVER THE MOON: A View From Orbit (NASA SP-362, 1978) discusses Van de Graaff * * * * * * * * * * * {{refend Impact craters on the Moon