Mensa (constellation)

Mensa (constellation)

Abbreviation Men
Genitive Mensae
Symbolism the Table Mountain
Right ascension 4 ~ 7.5
Declination −71 ~ −85.5
Family La Caille
Quadrant SQ1
Area 153 sq. deg. (75th)
Main stars 4
Stars with planets 2
Stars brighter than 3.00m none
Stars within 10.00 pc (32.62 ly) none
Brightest star α Men (5.09m)
Nearest star α Mensae
(33.10 ly, 10.15 pc)
Messier objects none
Meteor showers none
Visible at latitudes between +4° and −90°.
Best visible at 21:00 (9 p.m.) during the month of January.
The constellation Mensa as it can be seen by the naked eye.

Mensa is a constellation in the southern sky, created in the 18th century. Its name is Latin for table. It covers a keystone-shaped wedge of sky stretching from approximately 4h to 7.5h of right ascension, and −71 to −85.5 degrees of declination. Other than the south polar constellation of Octans, it is the most southerly of constellations. As a result, it is essentially unobservable from the Northern Hemisphere. Besides those already mentioned, its other neighbouring constellations are Chamaeleon, Dorado, Hydrus, and Volans. It is the only constellation named after a feature on Earth.


Mensa was created by Nicolas Louis de Lacaille out of dim Southern Hemisphere stars in honor of Table Mountain, a South African mountain. Although the stars of Mensa do not feature in any ancient mythology, the mountain it is named after has a rich mythology. Called "Tafelberg" in Dutch and German, the mesa has two neighboring mountains called "Devil's Peak" and "Lion's Head". Table Mountain features in the mythology of the Cape of Good Hope, notorious for its storms—the explorer Bartolomeu Dias saw the mesa as a mythical anvil for storms. Another myth relating to its dangers comes from Sinbad the Sailor, an Arabic folk hero who saw the mountain as a magnet pulling his ships to the bottom of the sea.[1]

Notable features


Mensa contains no bright stars, with Alpha Mensae its brightest star at a barely visible magnitude 5.09, making it the faintest constellation in the entire sky. Alpha Mensae is a solar-type star (spectral classification G5 V) 33 light-years from Earth, and is considered a good prospect for harboring an Earth-like planet. Pi Mensae, on the other hand, while also solar-type (G1) and at 59 light-years, has been found to have a large gas giant in an eccentric orbit crossing the habitable zone, which would effectively rule out the existence of any habitable planets.

Deep-sky objects

Mensa contains part of the Large Magellanic Cloud (the rest being in Dorado).

The first images taken by the Chandra X-Ray Observatory were of PKS 0637-752, a quasar in Mensa with a large gas jet visible in both optical and x-ray wavelengths.


  1. ^ Staal 1988, p. 259.

External links

  • The Deep Photographic Guide to the Constellations: Mensa
  • Star Tales – Mensa
  • Mensa Constellation at Constellation Guide