| Coordinates: | 41.6°N -43.4°W |
| Diameter: | 40 km |
| Depth: | 3.4 km |
| Colong: | 44 |
| Eponym: | Jean J. d'Ortous de Mairan |
Mairan is a lunar impact crater that is located on a highland peninsula between Oceanus Procellarum to the west and Mare Imbrium to the east. To the north-northeast is the comparably sized crater Sharp. Northwest of Mairan is the heavily eroded Louville.
The outer rim of Mairan has not been significantly eroded or impacted, and retains a sharp edge. The surface around Mairan is rough and irregular, with a multitude of many tiny craters, particularly to the south and west. The inner walls display some terracing, and flow down to a relatively flat interior floor.
Mairan is a crater of Upper (Late) Imbrian age.[1]
The volcanic complex, known as Mairan Hills or Mairan Domes, is composed of Mairan T together with three satellite domes (Mairan Northwest, Mairan Middle, and Mairan South). It was formed by two volcanic episodes 3.75 and 3.35 billion years ago, extruding a viscous silicic lava simultaneously with basalt eruptions in nearby mare. Most of volcanic complex, except for dome summits, is now buried under mare surface.[2]
In the mare, due west of Mairan, is a small lunar dome designated Mairan T with 3.8 km wide depression at the summit (in official IAU nomenclature "Mairan T" name refers only to the depression), believed to be a caldera The width of hill is about 7 km, and height is about 800 m. It is one of four unusually steep (with slopes reaching 22-27 degrees) and bright domes in area which are thought to be formed by very viscous, high-Si lava.
The composition of domes is changing from the north to south, with Mairan Northwest composed of pyroxenes with 30% quartz admixture, while Mairan South dome composed of nearly pure quartz, with extremely high thorium concentration of 83 ppm.[3]
There is a sinuous rille along the southwest edge of the highland peninsula containing Mairan. It is designated Rima Mairan, and follows a north–south course for a length of about 100 kilometers.
By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Mairan.
| Mairan | Latitude | Longitude | Diameter | |
|---|---|---|---|---|
| A | 38.6° N | 38.8° W | 16 km | |
| C | 38.6° N | 46.0° W | 7 km | |
| D | 40.9° N | 45.4° W | 10 km | |
| E | 37.8° N | 37.2° W | 6 km | |
| F | 40.3° N | 45.1° W | 9 km | |
| G | 40.9° N | 50.8° W | 6 km | |
| H | 39.3° N | 40.0° W | 5 km | |
| K | 40.8° N | 41.0° W | 6 km | |
| L | 39.0° N | 43.2° W | 6 km | |
| N | 39.2° N | 45.5° W | 6 km | |
| T | 41.7° N | 48.3° W | 3 km | |
| Y | 42.7° N | 44.0° W | 7 km |
. Patrick Moore . 2001 . On the Moon . . 978-0-304-35469-6 .
. Antonín Rükl . 1990 . Atlas of the Moon . . 978-0-913135-17-4 .
. Thomas William Webb . 1962 . Celestial Objects for Common Telescopes . 6th revised . Dover . 978-0-486-20917-3 .
. Ewen Whitaker . 2003 . Mapping and Naming the Moon . Cambridge University Press . 978-0-521-54414-6 .