Mensa is a small, faint constellation in the southern hemisphere, created by the French astronomer Nicolas Louis de Lacaille in the 18th century. Lacaille originally named it Mons Mensae, which was the Latin name for Table Mountain near Cape Town, South Africa, where he had previously made some important discoveries. Mensa means "table" in Latin. It is the southernmost constellation except Octans
and cannot be seen from the northern hemisphere at all.
The constellation Mensa occupies an area of 153 square degrees and contains one star with known planets. It can be seen at latitudes between +4° and -90° and is best visible at 9 p.m. during the month of January. Mensa is one of the 15 circumpolar constellations in the southern sky, never setting under the horizon.
Mensa does not have any bright stars. The brightest one, 
alpha Mensae, can barely be seen at magnitude 5.09. It is a main sequence dwarf, a G-type star similar to our Sun, approximately 33 light-years from Earth. Another notable star, 
pi Mensae, is a subgiant and also a G-type star, 59 light-years distant. It has a large gas giant, one of the largest planets ever discovered, in eccentric orbit. 
beta Mensae, the third brightest star, is a G-type giant with a magnitude of 5.3.
The constellation does not have any notable deep sky objects. It does, however, contain a part of the Large Magellanic Cloud, an irregular galaxy neighbouring our own, the Milky Way, which makes Mensa appear as if it were capped by a cloud. The greater part of the Large Magellanic Cloud is in the neighbouring constellation Dorado
Mensa belongs to the Lacaille family of constellations, along with Norma
Constellations directly bordering Mensa are Dorado