Libra (constellation)
15h 00m 00s, −15° 00′ 00″| Constellation | |
29th) | |
| Main stars | 4, 6 |
|---|---|
| Bayer/Flamsteed stars | 56 |
| Stars with planets | 4 |
| Stars brighter than 3.00m | 2 |
| Stars within 10.00 pc (32.62 ly) | 5 |
| Brightest star | Beta Librae (β Lib) (2.61m) |
| Messier objects | 0 |
| Meteor showers | May Librids |
| Bordering constellations | Serpens Caput Virgo Hydra Centaurus (corner) Lupus Scorpius Ophiuchus |
| Visible at latitudes between +65° and −90°. Best visible at 21:00 (9 p.m.) during the month of June. | |
Libra .svg){kind=small}
(♎︎). It is fairly faint, with no first magnitude stars, and lies between Virgo to the west and Scorpius to the east. Beta Librae
Features
Stars
Overall, there are 83 stars within the constellation's borders brighter than or equal to apparent magnitude 6.5.[a][2]
The brightest stars in Libra form a quadrangle that distinguishes it for the unaided observer. Traditionally, Alpha and Beta Librae are considered to represent the scales' balance beam, while Gamma and Sigma are the weighing pans.
Iota Librae is a complex multiple star, 377 light-years from Earth, with both optical and true binary components. The primary appears as a blue-white star of magnitude 4.5; it is a binary star indivisible in even the largest amateur instruments with a period of 23 years. The secondary, visible in small telescopes as a star of magnitude 9.4, is a binary with two components, magnitudes 10 and 11. There is an optical companion to Iota Librae; 25 Librae is a star of magnitude 6.1, 219 light-years from Earth and visible in binoculars. Mu Librae is a binary star divisible in medium-aperture amateur telescopes, 235 light-years from Earth. The primary is of magnitude 5.7 and the secondary is of magnitude 6.8.[3]
History and mythology
Libra was known in Babylonian astronomy as MUL Zibanu (the "scales" or "balance"), or alternatively as the Claws of the Scorpion. The scales were held sacred to the sun god Shamash, who was also the patron of truth and justice.[5]
It was also seen as the Scorpion's Claws in
In ancient Egypt the three brightest stars of Libra (α, β, and σ Librae) formed a constellation that was viewed as a boat.
The constellation
Libra is bordered by the head of Serpens to the north, Virgo to the northwest, Hydra to the southwest, the corner of Centaurus to the southwest, Lupus to the south, Scorpius to the east and Ophiuchus to the northeast. Covering 538.1 square degrees and 1.304% of the night sky, it ranks 29th of the 88 constellations in size.[2] The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Lib".[8] The official constellation boundaries, as set by Eugène Delporte in 1930, are defined by a polygon of 12 segments (illustrated in infobox). In the equatorial coordinate system, the right ascension coordinates of these borders lie between 14h 22m 08.08s and 16h 02m 17.23s, while the declination coordinates are between −0.47° and −30.00°.[9] The whole constellation is visible to observers south of latitude 60°N.[b]
Planetary systems
Libra is home to the
The family of candidate habitable planets was extended in late September 2010 to include exoplanets around
Deep-sky objects
Libra is home to one bright
Astrology
As of 2002[update], the Sun appears in the constellation Libra from October 31 to November 22. In
Namesakes
- Libra (AKA-12) was a United Statesnavy ship named after the constellation.
- Tropical Storm Tembin- Four tropical cyclones in the western Pacific have been given its Japanese name.
See also
- Constellation family
- Former constellations
- Libra (Chinese astronomy)
- Lists of stars by constellation
Notes
- ^ Objects of magnitude 6.5 are among the faintest visible to the unaided eye in suburban-rural transition night skies.[1]
- ^ While parts of the constellation technically rise above the horizon to observers between 60°N and 89°N, stars within a few degrees of the horizon are to all intents and purposes unobservable.[2]
References
- ^ Bortle, John E. (February 2001). "The Bortle Dark-Sky Scale". Sky & Telescope. Sky Publishing Corporation. Retrieved 3 April 2016.
- ^ a b c Ridpath, Ian. "Constellations: Lacerta–Vulpecula". Star Tales. Self-published. Retrieved 3 April 2016.
- ^ a b c d e f Ridpath & Tirion 2001, pp. 172–173.
- ^ "Naming Stars". IAU.org. Retrieved 8 August 2018.
- ^ Babylonian Star-lore by Gavin White, Solaria Pubs, 2008, page 175
- ^ a b c This article incorporates text from a publication now in the public domain: Chisholm, Hugh, ed. (1911). "Libra". Encyclopædia Britannica (11th ed.). Cambridge University Press.
- ^ Priskin, Gyula. "The Astral Myth of Osiris: the Decans of Taurus and Libra". ENiM 9 (2016), 79-111. Retrieved 22 September 2016.
- Bibcode:1922PA.....30..469R.
- ^ "Libra, Constellation Boundary". The Constellations. International Astronomical Union. Retrieved 3 April 2016.
- ^ Shiga, David (September 29, 2010), Found: first rocky exoplanet that could host life, New Scientist, retrieved September 30, 2010
- S2CID 2983930. Archived from the original(PDF) on 21 May 2009.
- ^ "Major Discovery: New Planet Could Harbor Water and Life". space.com. 24 April 2007.
- ^ "Department of Astronomy" (PDF). www.astro.washington.edu. Archived from the original (PDF) on 2013-09-22. Retrieved 2012-04-20.
- ^ "Earth-Like Planet Can Sustain Life : Discovery News". Discovery Channel. 2010-09-29. Archived from the original on 2012-11-19. Retrieved 2012-05-16.
- ^ csligman.com
Sources
- Ridpath, Ian; Tirion, Wil (2001), Stars and Planets Guide, Princeton University Press, ISBN 0-691-08913-2
- Ian Ridpath and Wil Tirion (2007). Stars and Planets Guide, Collins, London. ISBN 978-0-691-13556-4.
External links
- The Deep Photographic Guide to the Constellations: Libra
- Libra constellation
- Ian Ridpath's Star Tales – Libra
- Warburg Institute Iconographic Database (medieval and early modern images of Libra)
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