Mensa is the only constellation named after a real geographic feature on Earth — Table Mountain in Cape Town, named by 18th-century French astronomer Lacaille. The International Astronomical Union officially recognizes 88 constellations, ratified in 1922 with boundaries drawn by Eugène Delporte in 1930. This quiz mixes real IAU constellations — many obscure — with plausible-sounding fakes.
Each round presents 10 randomized questions from a pool of 50, with four multiple-choice options and instant feedback after every answer. Your final score comes with a performance tier and shareable results.
You'll learn the 12 zodiac constellations, Ptolemy's original 48, Lacaille's 14 'instrument' additions, the largest (Hydra) and smallest (Crux) constellations, retired ones like Argo Navis and Quadrans Muralis, and how to spot a made-up name by ear.
The International Astronomical Union (IAU) recognizes 88 official constellations, ratified in 1922 with formal boundaries drawn by Belgian astronomer Eugène Delporte in 1930.
Mensa is named after Table Mountain (Mons Mensae) in Cape Town, South Africa, where Nicolas-Louis de Lacaille observed the southern sky in the mid-1700s. It is the only constellation named for a terrestrial geographic feature.
Crux, the Southern Cross, is the smallest of the 88 constellations by area. Hydra is the largest.
Last updated: May 2026