Cha · Chamaeleontis
Chamaeleon Constellation
IAU constellation mapChaChamaeleon (Cha) is one of the 88 constellations recognised by the International Astronomical Union. It covers 132 square degrees of the southern sky in quadrant SQ2. Its brightest star is Alpha Chamaeleontis. The Latin genitive of the name is Chamaeleontis, used to form star names within the constellation. The IAU standardised all constellation boundaries in 1930.
Quick facts
- IAU name
- Chamaeleon
- Abbreviation
- Cha
- Latin genitive
- Chamaeleontis
- Hemisphere
- southern
- Area
- 132 sq deg
- Brightest star
- Alpha Chamaeleontis
- Quadrant
- SQ2
- Family
- Bayer
- Mythology origin
- Modern
- Discovery era
- Keyser and de Houtman, 1597-1598 (Bayer 1603)
Mythology
The Chameleon is a small southern constellation introduced by the Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman during their 1595–1597 voyage to the East Indies, first depicted on a celestial globe by Petrus Plancius in 1598 and published in Johann Bayer's Uranometria in 1603. The constellation represents the slow-moving lizard famous for changing colour. It covers 132 square degrees near the south celestial pole. Its brightest star, Alpha Chamaeleontis, is an F-type main-sequence star of magnitude 4.07 lying about 63 light-years from Earth. The constellation contains the Chamaeleon I dark nebula, an active stellar nursery where new stars are currently forming about 500 light-years away.
Overview
Chamaeleon is one of the 88 constellations formally recognised by the International Astronomical Union (IAU). It occupies 132 square degrees of sky in the southern hemisphere sky, best visible at latitudes between +45 and -90 degrees in March. The constellation belongs to the Bayer family of constellations. Its Latin genitive is Chamaeleontis, the form used when naming stars within the constellation — for example, the brightest star Alpha Chamaeleontis may appear in catalogues as Alpha Chamaeleontis or similar. The IAU standardised the boundaries of all 88 constellations in 1930 under the direction of Eugène Delporte, using straight lines of right ascension and declination to eliminate the ambiguities of earlier variable-boundary systems.
Notable stars
The brightest star in Chamaeleon is Alpha Chamaeleontis. Individual stars within Chamaeleon are conventionally named using Bayer designation — Greek letters followed by the Latin genitive of the constellation name (Chamaeleontis) — introduced by Johann Bayer in his 1603 star atlas Uranometria. Flamsteed numbers (numeric designators followed by Chamaeleon) were added by John Flamsteed in his 1712 catalogue. Variable stars, double stars, and deep-sky objects within the Chamaeleon boundary are catalogued by the IAU with the abbreviation Cha.
History and catalogue
Chamaeleon was introduced or documented by Keyser and de Houtman, 1597-1598 (Bayer 1603). The modern IAU constellation boundaries were formally established in 1930. The designation Cha is the official three-letter IAU abbreviation used in star catalogues, variable star designations, and positional references. The family classification 'Bayer' groups this constellation with others sharing a region of sky or a common historical source in astronomical literature.
Sources & further reading (2)
- official-iau — accessed 2026-05-06
- encyclopedia — accessed 2026-05-06
Frequently asked questions
What does the name Chamaeleon mean?
Chamaeleon is the Latin name used by the IAU to designate this constellation. The name comes from classical Latin and Greek astronomical tradition. In star catalogues, stars within Chamaeleon are designated using the genitive form of the name (e.g. Alpha Chamaeleon or similar Latin genitive forms) — a naming convention introduced by Johann Bayer in his 1603 atlas Uranometria and still in use today.
How large is Chamaeleon compared to other constellations?
Chamaeleon covers 132 square degrees of sky. The full sphere of the sky contains 41,253 square degrees, so Chamaeleon occupies about 0.3% of the total sky. For comparison, the largest constellation is Hydra at 1303 square degrees; the smallest is Crux at 68 square degrees.
When and where is Chamaeleon visible?
Chamaeleon is primarily a southern hemisphere constellation. Observers at high northern latitudes cannot see it; it is best appreciated from the southern tropics or high southern latitudes. The brightest star, Alpha Chamaeleontis, serves as the main visual anchor for locating the constellation. As with all constellations, the best viewing conditions are a dark sky away from artificial light pollution, with the constellation high enough above the horizon to minimise atmospheric absorption.
