Van de Graaff (crater)
Encyclopedia
Van de Graaff is an unusual lunar
formation that has the appearance of two merged crater
s, approximately in a figure-8
shape with no intervening rim separating the two halves. The crater is located on the far side of the Moon
, on the northeast edge of Mare Ingenii
. 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
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
in the vicinity of this formation that is stronger than the natural lunar field. This is most likely an indication of volcanic rock underneath the surface. The crater also has a slightly higher concentration of radioactive 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
impact site, and it is thought that powerful seismic wave
s from this event converged at this point. Most likely this energy created the grooved appearance as the tremors triggered landslide
s, although the grooves may also have been formed by deposited clumps of ejecta from the impact.
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...
formation that has the appearance of two merged 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...
s, approximately in a figure-8
Figure 8
Figure 8 may refer to:* 8 , in Arabic numeralsIn entertainment* Figure 8 , by American singer-songwriter Elliott Smith* "Figure of Eight" from the album Flowers in the Dirt by Paul McCartney...
shape with no intervening rim separating the two halves. The crater is located 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...
, on the northeast edge of Mare Ingenii
Mare Ingenii
Mare Ingenii is one of the few lunar mare features on the far side of the Moon. The mare sits in the Ingenii basin. This basin material is of the Pre-Nectarian epoch. The mare material located in Ingenii and the surrounding craters is of the Upper Imbrian epoch...
. The crater Birkeland
Birkeland (lunar crater)
Birkeland is a lunar impact crater that lies in the southern hemisphere on the far side of the Moon. This crater is attached to the central waist of the oddly shaped Van de Graaff crater formation, and may partly account for that crater's figure-8 shape...
is attached to the southeast rim, nestling against the slightly narrower "waist" of the formation. To the north is Aitken
Aitken (crater)
Aitken is a large lunar impact crater that lies on the far side of the Moon, named for Robert Grant Aitken, an American astronomer specializing in binary stellar systems. It is located to the southeast of the crater Heaviside, and north of the unusual formation Van de Graaff. Attached to the...
, and Nassau
Nassau (crater)
Nassau is a lunar impact crater on the Moon's far side. It abuts against the northeastern rim of the figure-8-shaped crater Van de Graaff. To the southeast of Nassau lies the crater Leeuwenhoek, and to the east is Orlov....
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
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...
in the vicinity of this formation that is stronger than the natural lunar field. This is most likely an indication of volcanic rock underneath the surface. The crater also has a slightly higher concentration of radioactive 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
Antipode
Antipode, Antipodes, or Antipodeans may refer to:* Antipodal point, the diametrically opposite point on a sphere* Antipodes Water Company, a premium bottled water brand...
of the Mare Imbrium
Mare Imbrium
Mare Imbrium, Latin for "Sea of Showers" or "Sea of Rains", is a vast lunar mare filling a basin on Earth's Moon and one of the larger craters in the Solar System. Mare Imbrium was created when lava flooded the giant crater formed when a very large object hit the Moon long ago...
impact site, and it is thought that powerful seismic wave
Seismic wave
Seismic waves are waves of energy that travel through the earth, and are a result of an earthquake, explosion, or a volcano that imparts low-frequency acoustic energy. Many other natural and anthropogenic sources create low amplitude waves commonly referred to as ambient vibrations. Seismic waves...
s from this event converged at this point. Most likely this energy created the grooved appearance as the tremors triggered landslide
Landslide
A landslide or landslip is a geological phenomenon which includes a wide range of ground movement, such as rockfalls, deep failure of slopes and shallow debris flows, which can occur in offshore, coastal and onshore environments...
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 mid-point that is closest to Van de Graaff.| Van de Graaff |
Latitude | Longitude | Diameter |
|---|---|---|---|
| C | 26.6° S | 172.8° E | 20 km |
| F | 26.8° S | 174.6° E | 20 km |
| J | 28.5° S | 174.1° E | 25 km |
| M | 30.6° S | 171.5° E | 19 km |
| Q | 27.6° S | 171.3° E | 15 km |