A constellation is an area on the celestial sphere in which a group of stars forms an imaginary outline or pattern, animal, creature, or an inanimate object.
MENSA is one of the faintest constellations in the Southern Celestial Hemisphere near the south celestial pole and associated with a Large Magellanic Cloud. This constellation was discovered by French astronomer Nicolas Louis de Lacaille, while studying the sky at the Cape of Good Hope during his 1750-1754 visit. Of all the 88 constellations, he named 14 of them. (see footnote)
MENSA in Latin means ‘table’ and in 1756 de Lacaille named the constellation 'Montagne de la Table', but later used a Latin name ‘Mons Mensae’. The English astronomer John Herschel suggested a shortened name, hence 'Mensa'.
This constellation consists of more than 20 stars, but the 4 prominent stars forming the ‘table-like’ pattern are the following:
- α Alpha Mensae (yellow colour) closest 33,26 light years from the Sun and brightest star
- β Beta Mensae (yellow colour) furthest 793.58 light years from the Sun
- γ Gamma Mensae (orange colour) 102.28 light years from the Sun
- η Eta Mensae (orange colour) 668.37 light years from the Sun
In addition to these stars taking the form of a table, a Large Magellanic Cloud (LMC) is visible near it, hence being called ‘Cape clouds’ as it relates to the cloud cover prominent over Table Mountain when the south-easterly stormy wind blew. It lies partially within Mensa's boundaries, whilst most of it lies in neighboring Dorado constellation. LMC is a satellite galaxy of the Milky Way, located at a distance of 163,000 light-years away and the third closest galaxy to our own.
When looking at the sky, it can be located using the Southern-Cross as anchor point, but visibility with naked eye is best at locations away from cities where light is darker, unless you own a telescope.
Footnote:
One of the craters on the Moon is named after him, called ‘La Caille’-crater, a lunar impact crater. The crater’s coordinates on the Moon are 23.8°S 1.1°E.