Ara (constellation)

Ara (constellation)

Abbreviation Ara[1]
Genitive Arae[1]
Pronunciation , genitive [1]
Symbolism the Altar[1]
Right ascension 16h 34m 16.9497s–18h 10m 41.3407s[2]
Declination −45.4859734°–−67.6905823°[2]
Family Hercules
Area 237 sq. deg. (63rd)
Main stars 8[1]
Stars with planets 7
Stars brighter than 3.00m 2
Stars within 10.00 pc (32.62 ly) 3
Brightest star β Ara (2.84m)
Nearest star Gliese 674
(14.80 ly, 4.54 pc)
Messier objects 0
Meteor showers None
Visible at latitudes between +25° and −90°.
Best visible at 21:00 (9 p.m.) during the month of July.

Ara is a southern constellation situated between Scorpius and Triangulum Australe. Its name is Latin for "altar". Ara was one of the 48 Greek constellations described by the 2nd century astronomer Ptolemy, and it remains one of the 88 modern constellations defined by the International Astronomical Union.

Notable features

The constellation Ara as it can be seen by the naked eye.


Ara contains part of the Milky Way to the south of Scorpius and thus has rich star fields.[1]

  • α Ara is a blue-white hued star of magnitude 2.8, 242 light-years from Earth.[1]
  • β Ara is an orange-hued supergiant of magnitude 2.8, 600 light-years from Earth.[1]
  • γ Ara is a blue-hued supergiant of magnitude 3.3, 1140 light-years from Earth.[1]
  • δ Ara is a blue-white hued star of magnitude 3.6, 187 light-years from Earth.[1]
  • ζ Ara is an orange-hued giant of magnitude 3.1, 574 light-years from Earth.[1]

The constellation's stars have no names in Western culture, but the Chinese call α Arae "Choo" ("club" or "staff"), and ε Arae "Tso Kang", meaning 'left guard'.

Deep-sky objects

The northwest corner of Ara is crossed by the galactic plane of the Milky Way and contains several open clusters (notably NGC 6200) and diffuse nebulae (including the bright cluster/nebula pair NGC 6188 and NGC 6193). The brightest of the globular clusters, sixth magnitude NGC 6397, lies at a distance of just 6,500 light-years (6.1×1016 km), making it one of the closest globular cluster to the solar system.[3]

Ara also contains Westerlund 1, a super star cluster that contains the red supergiant Westerlund 1-26, one of the largest stars known.

Although Ara lies close to the heart of the Milky Way, two spiral galaxies (NGC 6215 and NGC 6221) are visible near star η Arae.[3]

Open clusters

  • NGC 6193 is an open cluster containing approximately 30 stars with an overall magnitude of 5.0 and a size of 0.25 square degrees, about half the size of the full Moon. It is approximately 4200 light-years from Earth. It has one bright member, a double star with a blue-white hued primary of magnitude 5.6 and a secondary of magnitude 6.9. NGC 6193 is surrounded by NGC 6188, a faint nebula only normally visible in long-exposure photographs.[1]

Globular clusters

  • NGC 6352
  • NGC 6362
  • NGC 6397 is a globular cluster with an overall magnitude of 6.0; it is visible to the naked eye under exceptionally dark skies and is normally visible in binoculars. It is a fairly close globular cluster, at a distance of 10,500 light-years.[1]

Planetary Nebulae

  • The Stingray Nebula (Hen 3-1357), the youngest known planetary nebula as of 2010, formed in Ara; the light from its formation was first observable around 1987.
  • NGC 6326. A planetary nebula that might have a binary system at its center.


Johann Elert Bode's illustration of Ara, from his Uranographia (1801)

In illustrations, Ara is usually depicted as an altar with its smoke 'rising' southward.[4] However, depictions of Ara often vary in their details. In the early days of printing, a 1482 woodcut of Gaius Julius Hyginus's classic Poeticon Astronomicon depicts the altar as surrounded by demons.[5] Johann Bayer in 1603 depicted Ara as an altar with burning incense; the flames rise southward as in most atlases. Hyginus also depicted Ara as an altar with burning incense, though his Ara featured devils on either side of the flames. However, Willem Blaeu, a Dutch uranographer active in the 16th and 17th centuries, drew Ara as an altar designed for sacrifice, with a burning animal offering. Unlike most depictions, the smoke from Blaeu's Ara rises northward, represented by Alpha Arae. A more unusual depiction of Ara comes from Aratus, a Greek uranographer, in 270 BCE. He drew Ara as a lighthouse, where Alpha. Beta, Epsilon, and Zeta Arae represent the base, and Eta Arae represents the flames at the lighthouse's light.[6]


In ancient Greek mythology, Ara was identified as the altar where the gods first made offerings and formed an alliance before defeating the Titans.[1] The nearby Milky Way represents the smoke rising from the offerings on the altar.[7]


In Chinese astronomy, the stars of the constellation Ara lie within The Azure Dragon of the East (東方青龍, Dōng Fāng Qīng Lóng).[8]


USS Ara (AK-136) was a United States Navy Crater class cargo ship named after the constellation.

See also


  1. ^ Random House Dictionary
  1. ^ a b c d e f g h i j k l m Ridpath & Tirion 2001, pp. 82–83.
  2. ^ a b
  3. ^ a b Dunlop 2005.
  4. ^ Ridpath, Star Tales Ara.
  5. ^
  6. ^ Staal 1988, p. 230.
  7. ^ Staal 1988, p. 229.
  8. ^ AEEA 2006.


Online sources

External links

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