Vallis Alpes is a lunar

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...

 valley feature that bisects the Montes Alpes

Montes Alpes

Montes Alpes is a mountain range in the northern part of the Moon's near side. It was named after the Alps in Europe.This range forms the northeastern border of the Mare Imbrium lunar mare. To the west of the range is the level and nearly featureless mare, while on the eastern face is a more rugged...

 range. It extends 166 km from 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...

 basin, trending east-northeast to the edge of the Mare Frigoris

Mare Frigoris

Mare Frigoris is a lunar mare located just north of Mare Imbrium, and stretches east to north of Mare Serenitatis. The mare is in the outer rings of the Procellarum basin...

. The valley is narrow at both ends and widens to a maximum width of about 10 km along the middle stretch. 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 .

The valley floor is a flat, 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 surface that is bisected by a slender, cleft-like 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...

. (This cleft is a challenging target for telescope

Telescope

A telescope is an instrument that aids in the observation of remote objects by collecting electromagnetic radiation . The first known practical telescopes were invented in the Netherlands at the beginning of the 1600s , using glass lenses...

 observation from the Earth

Earth

Earth is the third planet from the Sun, and the densest and fifth-largest of the eight planets in the Solar System. It is also the largest of the Solar System's four terrestrial planets...

.) The sides of the valley rise from the floor to the surrounding highland terrain, a blocky, irregular surface. The southern face of the valley is straighter than the northern side, which is slightly bowed and uneven. The more rugged edges of the valley lie at the narrow west-southwest end that cuts through the mountain range. Most likely this valley is a graben

Graben

In geology, a graben is a depressed block of land bordered by parallel faults. Graben is German for ditch. Graben is used for both the singular and plural....

 that was subsequently flooded with magma from Mare Imbrium and Mare Frigoris.

This valley was discovered in 1727 by Francesco Bianchini

Francesco Bianchini

Francesco Bianchini was an Italian philosopher and scientist. He worked for the curia of three popes, including being camiere d`honore of Clement XI, and secretary of the commission for the reform of the calendar, working on the method to calculate the astronomically correct date for Easter in a...

.