Montes Riphaeus is an irregular range of 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...

 mountain

Mountain

Image:Himalaya_annotated.jpg|thumb|right|The Himalayan mountain range with Mount Everestrect 58 14 160 49 Chomo Lonzorect 200 28 335 52 Makalurect 378 24 566 45 Mount Everestrect 188 581 920 656 Tibetan Plateaurect 250 406 340 427 Rong River...

s that lie along the west-northwestern edge of Mare Cognitum

Mare Cognitum

Mare Cognitum is a lunar mare located in a basin or large crater which sits in the second ring of the Procellarum basin. The basin material is of the Lower Imbrian epoch, while the basaltic mare material is of the Upper Imbrian epoch...

, on the southeastern edge of Oceanus Procellarum

Oceanus Procellarum

Oceanus Procellarum is a vast lunar mare on the western edge of the near side of the Earth's Moon. Its name derives from the old superstition that its appearance during the second quarter heralded bad weather...

. The range trends generally from north-northeast to south-southwest. It includes a number of slender ridge lines with valleys flooded by intruding flows 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...

.

This range is located at selenographic coordinates 7.7° S, 28.1° W. It has a diameter of 189 km, although it is typically only about 30–50 km wide. The nearest feature of note is Euclides

Euclides (crater)

Euclides is a small lunar impact crater located near the eastern edge of Oceanus Procellarum, about 30 kilometers to the west of the Montes Riphaeus mountains. The mare in the vicinity is devoid of significant craters, but to the west is an area of low rises. The crater is named after the Greek...

, a small but prominent crater to the west. About 100 km to the north is the crater Lansberg

Lansberg (crater)

Lansberg is a lunar impact crater on the Mare Insularum. It can be located by following a line south-southwest from Copernicus to Reinhold, then southwest to Lansberg. The crater has a high rim and a central mountain. There are terraces along the inner walls, and the tops have slumped to produce a...

.

The range is called after the Riphean Mountains

Riphean Mountains

The Riphean Mountains are mountains mentioned by authors of classical antiquity , but whose location is unknown....

 in the geography of classical antiquity

Classical antiquity

Classical antiquity is a broad term for a long period of cultural history centered on the Mediterranean Sea, comprising the interlocking civilizations of ancient Greece and ancient Rome, collectively known as the Greco-Roman world...

.