 Lunar Orbiter 4 image | |
| Coordinates | 28°36′S47°42′W / 28.6°S 47.7°W Coordinates: 28°36′S47°42′W / 28.6°S 47.7°W |
|---|---|
| Diameter | 40 km |
| Depth | 1.2 km |
| Colongitude | 49° at sunrise |
| Eponym | Luigi Palmieri |
Palmieri is a lunar impact crater that lies to the southwest of the Mare Humorum, in the southwestern quadrant of the Moon's near side. It lies due south of the crater Liebig and east-northeast of the larger Fourier.
Lunar craters are impact craters on Earth's Moon. The Moon's surface has many craters, almost all of which were formed by impacts.
An impact crater is an approximately circular depression in the surface of a planet, moon, or other solid body in the Solar System or elsewhere, formed by the hypervelocity impact of a smaller body. In contrast to volcanic craters, which result from explosion or internal collapse, impact craters typically have raised rims and floors that are lower in elevation than the surrounding terrain. Impact craters range from small, simple, bowl-shaped depressions to large, complex, multi-ringed impact basins. Meteor Crater is a well-known example of a small impact crater on Earth.
Mare Humorum is a lunar mare. The impact basin it is located in is 425 kilometers across.
This crater formation has an eroded outer rim that has a gap along the southeastern side and a pair of narrow gaps along the northern rim. The remains of a small, flooded crater form the northern edge of the gap along the southeast. Just to the southwest of Palmieri is the small crater Palmieri E.
The interior floor of Palmieri has been flooded by lava, leaving a dark interior surface that has a similar albedo to the lunar mare to the northeast. This floor is joined with a long expanse of lava surface to the north of Palmieri that proceeds northwards until it reaches the area between Liebig and de Gasparis. The floor is marked by a system of rilles named the Rimae Palmieri that continue to the north and southeast beyond the crater perimeter. These narrow rifts extend for about 150 kilometers.
Lava is molten rock generated by geothermal energy and expelled through fractures in planetary crust or in an eruption, usually at temperatures from 700 to 1,200 °C. The structures resulting from subsequent solidification and cooling are also sometimes described as lava. The molten rock is formed in the interior of some planets, including Earth, and some of their satellites, though such material located below the crust is referred to by other terms.
Albedo is the measure of the diffuse reflection of solar radiation out of the total solar radiation received by an astronomical body. It is dimensionless and measured on a scale from 0 to 1.
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 composition, and hence appear dark to the naked eye. The maria cover about 16% of the lunar surface, mostly on the side visible from Earth. The few maria on the far side are much smaller, residing mostly in very large craters. The traditional nomenclature for the Moon also includes one oceanus (ocean), as well as features with the names lacus (lake), palus (marsh), and sinus (bay). The last three are smaller than maria, but have the same nature and characteristics.
