Palus Epidemiarum is a small lunar mare

Lunar mare

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 compositions, and...

 in the southwestern part 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...

's near side. It lies to the southwest of Mare Nubium

Mare Nubium

Mare Nubium is a lunar mare in the Nubium basin on the Moon's near side. The mare is located just to the southeast of Oceanus Procellarum. The actual basin is believed to be of Pre-Nectarian system, with the surrounding basin material being of the Lower Imbrian epoch. The mare material is of the...

, and southeast of Mare Humorum

Mare Humorum

Mare Humorum is a lunar mare. The impact basin it is located in is 825 kilometers across. It was not sampled by the Apollo program, so a precise age has not been determined. However, geological mapping indicates that it is intermediate in age between the Imbrium and Nectaris Basins, suggesting an...

. This feature forms a rough band of 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...

-flooded terrain that runs generally west–east, with a northward extension near the western end.

This mare is notable for a system of rille

Rille

Rille is typically used to describe any of the long, narrow depressions in the lunar surface that resemble channels. Typically a rille can be up to several kilometers wide and hundreds of kilometers in length...

s in the western end named the Rimae Ramsden, and for the wide Rima Hesiodus that extends from near the mid-point to the east-northeast roughly 300 km. The flooded crater Capuanus

Capuanus (crater)

Capuanus is a lunar crater that lies along the southern edge of the Palus Epidemiarum. The outer rim is eroded and indented by lesser crater impacts, with notches in the north, west, and southern parts of the rim. The interior floor has been resurfaced by basaltic lava, which is connected to the...

 occupies the southern center of the Palus Epidemiarum, and is attached to the southern edge. Near the western end is the flooded crater Ramsden

Ramsden (crater)

Ramsden is a lunar impact crater located on the western stretch of the Palus Epidemiarum. To the east-southeast is the crater Capuanus, and to the north lies Dunthorne....

, after which the Rimae Ramsden are named. The crater Cichus

Cichus (crater)

Cichus is a lunar impact crater that lies in the southwestern part of the Moon, at the eastern edge of Palus Epidemiarum. Just to the northeast and nearly contacting the rim is the lava-flooded crater remnant Weiss....

 forms the eastern end of the mare.

The northern extension of the mare reaches the outer rims of the crater pair Campanus

Campanus (crater)

Campanus is a lunar impact crater that is located on the southwestern edge of Mare Nubium. It forms a crater pair with Mercator just to the southeast. Along the southern rampart of Campanus is the small lunar mare named Palus Epidemiarum...

 and Mercator

Mercator (crater)

Mercator is a lunar crater that is located on the southwestern edge of Mare Nubium, in the southwest part of the Moon. It is located to the southeast of the crater Campanus, and the two are separated by a narrow, winding valley....

. A narrow valley between these craters joins Palus Epidemiarum with Mare Nubium, and a rille from the Rimae Ramsden follows the course of this cleft. The small double-walled crater Marth

Marth (lunar crater)

Marth is a small lunar crater located in the northwest part of the Palus Epidemiarum. To the northwest is the crater Dunthorne, and to the southwest lies Ramsden...

 lies at the southern mid-point of this northern extension.

The selenographic coordinates

Selenographic coordinates

Selenographic coordinates are used to refer to locations on the surface of Earth's moon. Any position on the lunar surface can be referenced by specifying two numerical values, which are comparable to the latitude and longitude of Earth...

 of this feature are 32.0° S, 28.2° W, and it is enclosed within a diameter of 286 km. Altimetry data from the Clementine

Clementine mission

Clementine was a joint space project between the Ballistic Missile Defense Organization and NASA...

 spacecraft

Spacecraft

A spacecraft or spaceship is a craft or machine designed for spaceflight. Spacecraft are used for a variety of purposes, including communications, earth observation, meteorology, navigation, planetary exploration and transportation of humans and cargo....

shows that this feature slopes downward from west to east, with a height difference of 2 km from end to end.

External links

• LPOD — Grand Central Station