 Mare Nectaris | |
| Coordinates | 15°12′S34°36′E / 15.2°S 34.6°E /-15.2; 34.6 |
|---|---|
| Diameter | 340 km (210 mi)[1] |
| Eponym | Sea of Nectar |
Mare Nectaris/ˈnɛktərɪs/ (Latinnectaris, the "Sea of Nectar") is a smalllunar mare or sea (a volcanic lava plain noticeably darker than the rest of theMoon's surface) located south ofMare Tranquillitatis southwest ofMare Fecunditatis, on the near side of the Moon.Montes Pyrenaeus borders the mare to the east andSinus Asperitatis fuses to its northwestern edge. It is 84,000 square kilometers in size.[2]
Several large craters are situated at the borders of Mare Nectaris. The biggest one is lava-filledFracastorius (124 km), which fuses with the southern coast of the Sea. A prominent trio of 100-km cratersTheophilus,Cyrillus andCatharina is located near northwestern coast. Other notable feature is a "ghost crater"Daguerre, almost entirely covered with lava, in the northern part of Mare Nectaris.[3]
Mare Nectaris is located in the central part of 860-km-diameterimpact basin, which was formed 3.8–3.9 billion years ago. This event marks the beginning ofNectarian period of thelunar geologic timescale.[4][5] The best-preserved part of the rim of this basin is calledRupes Altai, in the southwest part of the basin.
Lava filling of Mare Nectaris is younger than the basin itself. The mare material is approximately 1000m in depth, and mainly of theNectarian period and theLower Imbrian epoch, with the mare material of theUpper Imbrian epoch. The craterTheophilus on the northeastern side of the mare is of theEratosthenian period. Thus, the crater is younger than the mare to its southeast. Enough subsidence has occurred to open a few arcuategrabens on the western margin of the mare.[6]
Amass concentration (mascon), or gravitational high, was identified in the center of Mare Nectaris from Doppler tracking of the fiveLunar Orbiter spacecraft in 1968.[7] The mascon was confirmed and mapped at higher resolution with later orbiters such asLunar Prospector andGRAIL.
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