Lacus Felicitatis

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Lacus Felicitatis
Coordinates18°30′N 5°24′E / 18.5°N 5.4°E / 18.5; 5.4Coordinates: 18°30′N 5°24′E / 18.5°N 5.4°E / 18.5; 5.4
Diameter98 km

Lacus Felicitatis (Latin for "Lake of Happiness")[1] is a small patch of the lunar surface that has been inundated by flows of lava, leaving a level patch with a lower albedo than the surrounding ground. It is located in Terra Nivium, an area of continental ground to the north of the Mare Vaporum. About 70–80 km to the northeast of this area are the Montes Haemus, along the southwestern edge of the Mare Serenitatis.

The selenographic coordinates of the centre of Lacus Felicitatis are 18.5° N, 5.4° E, and it has a maximum extent of 98 km.[1] In outline it has a bent shape, with a wing to the northwest and another to the east. The border is somewhat uneven, and it is surrounded by rugged lunar surface.

Three tiny craters within this formation have been assigned names by the IAU. These are listed below.

Crater Coordinates Diameter Name source
Dag 18.7° N, 5.3° E 0.5 km Scandinavian masculine name
Ina 18.6° N, 5.3° E 3 km Latin feminine name
Osama 18.6° N, 5.2° E 0.5 km Arabic masculine name

Ina is a semi-circular depression that is only about 30 m deep and is difficult to image from the Earth. In November 2006, it was suggested that Ina was the result of a gas eruption in the last 10 million years.[2][3]

Apollo 17 Mapping camera image of Ina (center)
Lacus Felicitatis's crater Ina gives signs of recent geological activity


  1. ^ a b "Lacus Felicitatis". Gazetteer of Planetary Nomenclature. USGS Astrogeology Research Program.
  2. ^ "Is the Moon Still Alive?". NASA. November 9, 2006. Retrieved 2007-07-30.
  3. ^ Schultz, Peter H., Matthew I. Staid & Carlé M. Pieters, Lunar activity from recent gas release, Nature 444, 184-186 (9 November 2006) doi:10.1038/nature05303 Bibcode2006Natur.444..184S Abstract

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