Chamaeleon (the Chameleon) is a small, faint constellation in the far southern sky. Introduced by Dutch astronomer Petrus Plancius in the late 16th century, it takes its name from the color-changing reptile found in Africa and other warm regions.
Although its brightest stars are only around fourth magnitude, Chamaeleon contains something particularly interesting: an extensive complex of molecular clouds where new stars are forming, along with young stellar groups and one of the southernmost planetary nebulae visible through amateur telescopes.
Where Is Chamaeleon and When Can You See It?
Chamaeleon is the 79th-largest constellation, covering approximately 132 square degrees of the southern sky. It lies close to the South Celestial Pole, south of Crux, and borders Apus, Carina, Mensa, Musca, Octans, and Volans.
The best time to observe Chamaeleon is March through May, particularly April, when it is well positioned in the evening sky. The constellation is circumpolar from many southern latitudes, meaning it never sets below the horizon. However, it cannot be seen from Britain or most of the Northern Hemisphere.
To locate Chamaeleon, begin with the bright stars of the Southern Cross (Crux) and look farther south, toward the South Celestial Pole. Its brightest stars — Alpha, Gamma, and Beta Chamaeleontis — are relatively faint, so a dark sky and a detailed star chart are helpful.
History of the Chamaeleon Constellation
Chamaeleon was introduced by Petrus Plancius using observations gathered by Dutch navigators Pieter Dirkszoon Keyser and Frederick de Houtman during voyages to the East Indies in the late 1500s. It appeared in Johann Bayer’s 1603 star atlas, Uranometria, and is now one of the 88 constellations recognized by the International Astronomical Union.
The constellation represents a chameleon, a reptile best known for its independently moving eyes, grasping feet, and ability to change skin color. Like several other southern constellations introduced during this period, Chamaeleon was named after an animal unfamiliar to many Europeans.
Because it lies so far south, it was not recognized by ancient Greek astronomers and has no established classical mythology.
Notable Stars in Chamaeleon
Image Credit: Torsten Bronger Alpha Chamaeleontis – The constellation’s brightest star, an F-type giant approximately 63 light-years away, shining at magnitude 4.1. It is somewhat hotter, larger, and more luminous than the Sun.
- Gamma Chamaeleontis – An orange-red giant approximately 400 light-years away, with an apparent magnitude of about 4.1. Its greatly expanded outer atmosphere gives it a cooler surface temperature than the Sun.
- Beta Chamaeleontis – A hot blue-white main-sequence star approximately 270 light-years away, shining at magnitude 4.2. It rotates rapidly and is considerably more massive than the Sun.
- Delta Chamaeleontis – A visual double consisting of Delta¹, an orange giant, and Delta², a hotter blue-white star. The two are easily distinguished in a small telescope under suitable conditions.
- R Chamaeleontis – A Mira-type variable star whose brightness changes dramatically over a period of roughly 334 days as its outer layers pulsate.
- CT Chamaeleontis – A young T Tauri star associated with the Chamaeleon star-forming region. It has a widely separated, low-mass companion that has been studied through direct imaging.
Notable Deep-Sky Objects in Chamaeleon
Chamaeleon contains no Messier objects, but its molecular clouds, young stars, and faint planetary nebula make it an interesting region for astronomers studying stellar birth and evolution.
Chamaeleon Cloud Complex — A Nearby Stellar Nursery
The Chamaeleon Cloud Complex is a collection of dark molecular clouds located roughly 500–700 light-years away. Its three principal regions — Chamaeleon I, II, and III — contain cold gas and dust that can collapse under gravity to form new stars.
Chamaeleon I is especially active, containing numerous young stars, protostars, and circumstellar disks. Many of these objects are T Tauri stars, which are still contracting toward the main sequence.
Astronomers study these clouds to understand how stars and planetary systems develop during their earliest stages. Although the clouds are extensive, they are difficult to observe visually because much of their material is dark. Their structure is best revealed through infrared observations and long-exposure photography.
Eta Chamaeleontis Cluster — A Young Stellar Group
The Eta Chamaeleontis Cluster (Mamajek 1) is a nearby group of young stars approximately 300 light-years away. Its members are thought to be only around 8–10 million years old, making the group extremely young compared with the Sun’s age of approximately 4.6 billion years.
The cluster was initially identified through a small number of prominent members, but subsequent studies have revealed a larger population of associated stars.
Its relative proximity makes it valuable for studying the early evolution of stars and their surrounding planetary disks.
NGC 3195 — A Southern Planetary Nebula
NGC 3195 is a planetary nebula approximately 5,500 light-years away, with an apparent magnitude around 11.6. It formed when an aging star expelled its outer atmosphere, leaving a hot stellar remnant that illuminates the surrounding gas.
NGC 3195 is one of the southernmost planetary nebulae known and appears as a small, faint patch through moderate-sized amateur telescopes. Under favorable conditions, larger instruments may reveal its slightly elongated shape, although its finer structure is best appreciated in astronomical photographs.
Other Deep-Sky Objects
Other objects in Chamaeleon include the galaxies NGC 3149 and NGC 3620, both challenging targets for larger telescopes.
The constellation also contains numerous faint young stars and infrared sources associated with its molecular clouds, making it a particularly important region for research into star formation.