Pallas (crater)
Encyclopedia
Pallas is a heavily eroded lunar
crater
located to the north of the Sinus Medii
. To the northwest is the smaller but less worn crater Bode
. Pallas shares a low wall with the crater Murchison
that is attached to the southeast, and there are two gaps in the shared rim.
The outer wall of Pallas is worn, notched, and somewhat distorted in shape. The associated crater Pallas A lies across the northwest rim. The inner floor of Pallas has been flooded by lava
, leaving a relatively flat surface. The crater possesses a central peak complex.
Dr. Leon H. Stuart took a picture of the Moon that appeared to show a flare of light about 16 km southeast of Pallas. The flare was estimated to last for about 8–10 seconds. The report was published in a 1956 issue of The Strolling Astronomer, a newsletter. However the incident was dismissed by professionals of the period as more likely a meteoroid
entering the Earth's atmosphere
.
Many years later Dr. Bonnie Buratti of JPL
saw the photograph and decided to investigate. Assisted by a graduate student, she identified a 1.5 km. diameter crater imaged by the Clementine spacecraft
. The crater has the correct size, shape, and albedo
to match the expected impact energy. Some astronomers now agree that Dr. Stuart may indeed have photographed an asteroid impact on 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...
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...
located to the north of the Sinus Medii
Sinus Medii
Sinus Medii is a small lunar mare that is located at the intersection of the Moon's equator and prime meridian. As seen from the Earth, this feature is located in the central part of the Moon's near side, and it is the point closest to the Earth...
. To the northwest is the smaller but less worn crater Bode
Bode (crater)
Bode is a small crater located near the central region of the Moon, to the northwest of the joined craters Pallas and Murchison. It lies on a region of raised surface between the Mare Vaporum to the northeast, Sinus Aestuum to the west, and Sinus Medii to the southeast.This crater is bowl-shaped,...
. Pallas shares a low wall with the crater Murchison
Murchison (crater)
Murchison is a lunar crater on the north edge of the Sinus Medii, named in honour of the geologist Sir Roderick Murchison. It shares a section of rim with the crater Pallas. To the southeast on the mare is the circular crater Chladni, and to the northeast is Ukert. Farther to the east is the...
that is attached to the southeast, and there are two gaps in the shared rim.
The outer wall of Pallas is worn, notched, and somewhat distorted in shape. The associated crater Pallas A lies across the northwest rim. The inner floor of Pallas 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 relatively flat surface. The crater possesses a central peak complex.
Lunar flare
On November 15, 1953, the physician and amateur astronomerAstronomer
An astronomer is a scientist who studies celestial bodies such as planets, stars and galaxies.Historically, astronomy was more concerned with the classification and description of phenomena in the sky, while astrophysics attempted to explain these phenomena and the differences between them using...
Dr. Leon H. Stuart took a picture of the Moon that appeared to show a flare of light about 16 km southeast of Pallas. The flare was estimated to last for about 8–10 seconds. The report was published in a 1956 issue of The Strolling Astronomer, a newsletter. However the incident was dismissed by professionals of the period as more likely a meteoroid
Meteoroid
A meteoroid is a sand- to boulder-sized particle of debris in the Solar System. The visible path of a meteoroid that enters Earth's atmosphere is called a meteor, or colloquially a shooting star or falling star. If a meteoroid reaches the ground and survives impact, then it is called a meteorite...
entering the Earth's atmosphere
Atmosphere
An atmosphere is a layer of gases that may surround a material body of sufficient mass, and that is held in place by the gravity of the body. An atmosphere may be retained for a longer duration, if the gravity is high and the atmosphere's temperature is low...
.
Many years later Dr. Bonnie Buratti of JPL
Jet Propulsion Laboratory
Jet Propulsion Laboratory is a federally funded research and development center and NASA field center located in the San Gabriel Valley area of Los Angeles County, California, United States. The facility is headquartered in the city of Pasadena on the border of La Cañada Flintridge and Pasadena...
saw the photograph and decided to investigate. Assisted by a graduate student, she identified a 1.5 km. diameter crater imaged by the Clementine spacecraft
Clementine mission
Clementine was a joint space project between the Ballistic Missile Defense Organization and NASA...
. The crater has the correct size, shape, and 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...
to match the expected impact energy. Some astronomers now agree that Dr. Stuart may indeed have photographed an asteroid impact on the Moon.
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 Pallas.| Pallas | Latitude | Longitude | Diameter |
|---|---|---|---|
| A | 6.0° N | 2.3° W | 11 km |
| B | 4.2° N | 2.6° W | 4 km |
| C | 4.5° N | 1.1° W | 6 km |
| D | 2.4° N | 2.6° W | 4 km |
| E | 4.0° N | 1.4° W | 26 km |
| F | 3.4° N | 1.3° W | 18 km |
| H | 4.6° N | 1.5° W | 5 km |
| N | 7.0° N | 0.5° E | 6 km |
| V | 1.7° N | 1.5° W | 3 km |
| W | 3.6° N | 1.3° W | 3 km |
| X | 5.2° N | 3.2° W | 3 km |