Altar · pronounced Ara. Ara, meaning “Altar,” is an official IAU constellation centred near right ascension 17.2 hours and declination -56°. Its observing character is defined by the named stars and targets below. Ara represents the altar on which the Olympian gods swore alliance before fighting the Titans in a common Greek interpretation. Ptolemy catalogued it, and early atlases often drew its smoke flowing south along the Milky Way. The line figure is only a guide: the IAU boundary is the scientifically meaningful region, while historical and cultural interpretations require their own context.
About Ara
Ara is one of the 88 constellations recognized by the International Astronomical Union. Its standard three-letter abbreviation is Ara, and astronomers use the genitive form Arae when naming stars associated with it. The constellation's reference position lies around right ascension -6.8 hours and declination -56 degrees.
Its location places it in the southern sky. For a typical mid-latitude observer, this part of the celestial sphere is especially well placed during summer evenings. Exact visibility depends on latitude, local horizon, date and time.
History and mythology of Ara
Origins and cultural history
Ara represents the altar on which the Olympian gods swore alliance before fighting the Titans in a common Greek interpretation. Ptolemy catalogued it, and early atlases often drew its smoke flowing south along the Milky Way.
From figure to official region
The IAU retained Altar as one of 88 official constellations in 1922; Eugène Delporte’s boundaries later turned the traditional figure into an exact cataloguing region.
How to find Ara
- Find Alpha and Beta Centauri, then follow the Milky Way southeast past Lupus.
- Ara lies between Scorpius’s tail and Triangulum Australe.
- Identify close-bright Alpha and Beta Arae before tracing the fainter altar.
- Use binoculars on NGC 6397; a telescope begins resolving its outer stars from southern sites.
Bright stars in Ara
Beta Arae
Notable star- Magnitude
- 2.85
- Distance
- about 650 light-years
Orange supergiant, marginally brighter than Alpha Arae.
Alpha Arae
Notable star- Magnitude
- 2.95
- Distance
- about 270 light-years
Hot Be star surrounded by a rotating gas disk.
Zeta Arae
Notable star- Magnitude
- 3.13
- Distance
- about 490 light-years
Luminous orange giant.
Gamma Arae
Notable star- Magnitude
- 3.34
- Distance
- about 1,100 light-years
Massive blue supergiant and spectroscopic binary.
Deep-sky objects in Ara
NGC 6397
One of the nearest globular clusters and among the first recognized core-collapsed examples.
NGC 6193
Young cluster containing hot O stars that illuminate nearby gas.
NGC 6188
Bright-rimmed star-forming cloud sculpted by NGC 6193.
Stingray Nebula (Hen 3-1357)
Very young planetary nebula observed to change markedly over decades.
Interesting facts about Ara
- Ara’s traditional name refers to altar, while its official IAU boundary defines a precise region of the sky.
- Beta Arae, at magnitude 2.85, is a key star in Ara. Orange supergiant, marginally brighter than Alpha Arae.
- NGC 6397 is a notable globular cluster in Ara. One of the nearest globular clusters and among the first recognized core-collapsed examples.
- NGC 6193, a open cluster, is another observing target within the constellation.
- Ara represents the altar on which the Olympian gods swore alliance before fighting the Titans in a common Greek interpretation.