Coalsack Nebula

Coalsack Nebula
Dark nebula
The Coalsack Nebula, taken by the Wide Field Imager on the MPG/ESO 2.2-metre telescope
Observation data: J2000.0 epoch
Right ascension12h 50m
Declination−62° 30′
Distance587 ly   (180 pc)
Apparent magnitude (V)–
Apparent dimensions (V)7° × 5°
ConstellationCrux
Physical characteristics
Radius30–35 ly
Absolute magnitude (V)–
Notable features–
DesignationsCaldwell 99
See also: Lists of nebulae

The Coalsack Nebula (Southern Coalsack, or simply the Coalsack) is a dark nebula, which is visible to the naked eye as a dark patch obscuring part of the Milky Way east of Acrux (Alpha Crucis) in the constellation of Crux.

General information

The Coalsack Nebula covers nearly 7° by 5° and extends into the neighboring constellations Centaurus and Musca. The first observation by a European was reported by Vicente Yáñez Pinzón in 1499. It was named "il Canopo fosco" (the dark Canopus) by Amerigo Vespucci and was also called "Macula Magellani" (Magellan's Spot) or "Black Magellanic Cloud" in opposition to the Magellanic Clouds. The Coalsack is traditionally recognized as a dark constellation by many cultures.

Historically any other dark cloud in the night sky was called a "coalsack". Richard Hinckley Allen in 1899 called a different dark nebula in Cygnus the Northern Coalsack.

A depiction of the emu in the sky known as weitj. The weitj in the sky is male, and you can see them guarding their eggs. During Makuru (the coldest and wettest time of the year, that falls across June and July), which is an Australian Aboriginal constellation consisting of dark clouds rather than of stars. The European constellation on the right is Crux, or the Southern Cross, and on the left is Scorpius. The head of the emu is the Coalsack.

In Australian Aboriginal astronomy, the Coalsack forms the head of the emu in the sky in several Aboriginal cultures. The emu has different names in different Aboriginal languages; for example, a Gamilaraay name is Gawaargay, and a Wergaia name is Tchingal. Amongst the Wardaman people, it is said to be the head and shoulders of a law-man watching the people to ensure they do not break traditional law. According to a legend reported by W. E. Harney, this being is called Utdjungon and only adherence to the tribal law by surviving tribe members could prevent him from destroying the world with a fiery star. There is also a reference by Gaiarbau (1880) regarding the coalsacks replicating bora rings on Earth. These astronomical sites allowed the spirits to continue ceremony similar to their human counterparts on Earth. As bora grounds are generally located on the compass points north–south, the southern coal sack indicates the ceremonial ring.[citation needed]

In Inca astronomy this nebula was called Yutu, after a partridge-like South American bird, the tinamou. (See also Andean dark constellations.)

On the Indonesian island of Bali, it is called Bubu Bosor, a leaky fish trap.

The Coalsack Nebula appeared in Kenji Miyazawa's story Night on the Galactic Railroad, where the protagonist, Giovanni, experiences his friend, Campanella, departing to his personal afterlife referred to as "True Heaven" where he sees his dead mother waiting for him. Giovanni is unable to see True Heaven, and is represented, instead, as the empty, black Coalsack to Giovanni.[citation needed]

The Coalsack Nebula and the galactic area surrounding it played a large role in Jerry Pournelle's CoDominium Universe, particularly The Mote in God's Eye and the sequel The Gripping Hand, both co-authored with Larry Niven. In these novels, a human-colonized system, New Caledonia, is on the opposite side of the Coalsack from Earth. Set against the Coalsack is a red supergiant, and between the supergiant and New Caledonia is a yellow F6 star, known as "The Mote in God's Eye".[citation needed]

References

  1. ↑ "A Cosmic Sackful of Black Coal". Retrieved 15 October 2015.
  2. 1 2 Franco, G.P.A. (2000). "Interstellar Na I D lines towards the Southern Coalsack". Monthly Notices of the Royal Astronomical Society. 315 (3): 611–621. Bibcode:2000MNRAS.315..611F. doi:10.1046/j.1365-8711.2000.03434.x.
  3. ↑ "Coalsack Nebula". SIMBAD. Centre de données astronomiques de Strasbourg. Retrieved 2018-09-30.
  4. ↑ Darling, David J. (2004). The universal book of astronomy: from the Andromeda Galaxy to the zone of avoidance. Hoboken, New Jersey: Wiley. p. 351. ISBN 0471265691.
  5. 1 2 "The Coalsack and the Southern Cross". ESO. 3 December 2009. Retrieved 1 October 2018.
  6. ↑ O'Meara, Stephen James (2012-04-23). "Where is the Northern Coalsack?". Astronomy.com. Retrieved 2023-02-10.
  7. ↑ Azkarrula, Youla; ASE Tech Team. "Gawaargay". All Skies Encyclopaedia. IAU Working Group on Star Names. Retrieved 29 October 2026.
  8. ↑ Hamacher, Duane W.; Frew, David J. (2010). "An aboriginal Australian record of the great eruption of Eta Carinae". Journal of Astronomical History and Heritage. 13 (3): 220–234. arXiv:1010.4610. Bibcode:2010JAHH...13..220H. doi:10.3724/SP.J.1440-2807.2010.03.06. S2CID 118454721.
  9. ↑ Songs of the Songmen, 28–30.
  10. ↑ James B. Kaler (2002). The Hundred Greatest Stars. New York: Springer Science & Business Media. p. 5. ISBN 978-0-387-95436-3.
  11. ↑ A. F. Aveni, ed. (2010). Archaeoastronomy in the New World : American primitive astronomy : proceedings of an international conference held at Oxford University, September, 1981. Cambridge: Cambridge University Press. ISBN 978-0521125475.
  12. ↑ Azkarrula, Youla; Hoffmann, Susanne M. "Bubu Bosor". All Skies Encyclopaedia. IAU Working Group on Star Names. Retrieved 29 October 2026.