Mensa is a constellation in the Southern Celestial Hemisphere near the south celestial pole, one of twelve constellations drawn up in the 18th century by French astronomer Nicolas-Louis de Lacaille. Its name is Latin for table, though it originally commemorated Table Mountain and was known as Mons Mensae. One of the eighty-eight constellations designated by the International Astronomical Union (IAU), it covers a keystone-shaped wedge of sky 153.5 square degrees in area. Other than the south polar constellation of Octans, it is the most southerly of constellations and is observable only south of the 5th parallel of the Northern Hemisphere.