Posidonius (crater)

Posidonius

Mosaic of Lunar Orbiter 4 images (spots in lower left are blemishes on original)
Diameter	95 km
Depth	2.3 km
Colongitude	343° at sunrise
Eponym	Posidonius

Oblique view of Posidonius from Apollo 17. Note that the lava which flooded the crater reached its rim and is clearly above the mare plain to the west (left).

Posidonius is a lunar impact crater that is located on the north-eastern edge of Mare Serenitatis, to the south of Lacus Somniorum. The crater Chacornac is attached to the southeast rim, and to the north is Daniell.

The rim of Posidonius is shallow and obscured, especially on the western edge, and the interior has been overlain by a lava flow in the past. The crater ramparts can still be observed to the south and east of the crater rim, and to a lesser degree to the north.

There is a smaller, semi-circular rim of a concentric, flooded crater within the main rim, offset towards the eastern edge. There is no central peak, but the floor is hilly and laced with a rille system named the Rimae Posidonius. The floor is also slightly bulged due to the past lava uplift, which also likely produced the complex of rilles. The northeast rim is interrupted by the smaller crater Posidonius B. Within the crater rim, offset just to the west of center is another smaller crater Posidonius A.

On the Mare Serenitatis surface near Posidonius is a notable system of wrinkle ridges that parallel the nearby shore. These are designated the Dorsa Smirnov. At the peak of these ridges is a small craterlet with a diameter of 2 km. This craterlet is surrounded by a patch of high-albedo material, and is an example of a lunar bright spot. This peak was formerly designated Posidonius Gamma (γ).

Posidonius Gamma was first observed by the lunar cartographer Julius Schmidt in 1857, who noted the similarity to the bright patch surrounding the crater Linné.

Satellite craters

By convention these features are identified on lunar maps by placing the letter on the side of the crater midpoint that is closest to Posidonius.

Posidonius	Latitude	Longitude	Diameter
A	31.7° N	29.5° E	11 km
B	33.1° N	30.9° E	14 km
C	31.1° N	29.6° E	2 km
E	30.5° N	19.7° E	3 km
F	32.8° N	27.1° E	6 km
G	34.8° N	27.2° E	5 km
J	33.8° N	30.7° E	22 km
M	34.3° N	30.0° E	10 km
N	29.7° N	21.0° E	6 km
P	33.6° N	27.5° E	15 km
W	31.6° N	20.1° E	3 km
Y	30.0° N	24.9° E	2 km
Z	30.7° N	22.9° E	6 km

References

• Andersson, L. E.; Whitaker, E. A. (1982). NASA Catalogue of Lunar Nomenclature. NASA RP-1097. {{cite book}}: Invalid |ref=harv (help)
• Blue, Jennifer (July 25, 2007). "Gazetteer of Planetary Nomenclature". USGS. Retrieved 2007-08-05. {{cite web}}: Invalid |ref=harv (help)
• Bussey, B.; Spudis, P. (2004). The Clementine Atlas of the Moon. New York: Cambridge University Press. ISBN 978-0-521-81528-4. {{cite book}}: Invalid |ref=harv (help)
• Cocks, Elijah E.; Cocks, Josiah C. (1995). Who's Who on the Moon: A Biographical Dictionary of Lunar Nomenclature. Tudor Publishers. ISBN 978-0-936389-27-1. {{cite book}}: Invalid |ref=harv (help)
• McDowell, Jonathan (July 15, 2007). "Lunar Nomenclature". Jonathan's Space Report. Retrieved 2007-10-24. {{cite web}}: Invalid |ref=harv (help)
• Moore, Patrick (2001). On the Moon. Sterling Publishing Co. ISBN 978-0-304-35469-6. {{cite book}}: Invalid |ref=harv (help)
• Price, Fred W. (1988). The Moon Observer's Handbook. Cambridge University Press. ISBN 978-0-521-33500-3. {{cite book}}: Invalid |ref=harv (help)
• Rükl, Antonín (1990). Atlas of the Moon. Kalmbach Books. ISBN 978-0-913135-17-4. {{cite book}}: Invalid |ref=harv (help)
• Webb, Rev. T. W. (1962). Celestial Objects for Common Telescopes (6th revised ed.). Dover. ISBN 978-0-486-20917-3. {{cite book}}: Invalid |ref=harv (help)
• Whitaker, Ewen A. (1999). Mapping and Naming the Moon. Cambridge University Press. ISBN 978-0-521-62248-6. {{cite book}}: Invalid |ref=harv (help)
• Wlasuk, Peter T. (2000). Observing the Moon. Springer. ISBN 978-1-85233-193-1. {{cite book}}: Invalid |ref=harv (help)