Libra (constellation)

**Libra**  is a constellation of the zodiac and is located in the Southern celestial hemisphere. Its name is Latin for weighing scales. Its old astronomical symbol is  (♎︎).  It is fairly faint, with no first magnitude stars, and lies between Virgo to the west and Scorpius to the east. Beta Librae, also known as Zubeneschamali, is the brightest star in the constellation. Three star systems are known to have planets.

## Features
### Stars
Overall, there are 83 stars within the constellation's borders brighter than or equal to apparent magnitude 6.5.) was formerly known as Gamma Scorpii despite being well inside the boundaries of Libra. It was not redesignated as Sigma Librae until 1851 by Benjamin A. Gould.

## History and mythology
*, a set of constellation cards published in London c.1825]]

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. Since these times, Libra has been associated with law, fairness and civility.

It was also seen as the Scorpion's Claws in ancient Greece. This is the name used repeatedly by Aratus, which made it widespread in Hellenistic times: "few conspicuous stars the Claws can boast,
and their dim light mid brighter gems is lost" In Arabic *zubānā* means "scorpion's claws", and likely similarly in other Semitic languages: this resemblance of words may be why the Scorpion's claws became the Scales. Indeed, Zubenelgenubi and Zubeneschamali, the names of the constellation's two main stars, in Arabic mean "southern claw" and "northern claw" respectively. It has also been suggested that the scales are an allusion to the fact that when the sun entered this part of the ecliptic at the autumnal equinox, the days and nights are equal. Libra is not mentioned by Eudoxus or Aratus as a constellation. It only became a constellation in ancient Rome, when it began to represent the scales held by Astraea, the goddess of justice, associated with Virgo in the Greek mythology.

## 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&nbsp;square degrees and 1.304% of the night sky, it ranks 29th of the 88 constellations in size. The three-letter abbreviation for the constellation, as adopted by the International Astronomical Union in 1922, is "Lib". 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  and , while the declination coordinates are between −0.47° and −30.00°. The whole constellation is visible to observers south of latitude 60°N.

### Planetary systems
Libra is home to the Gliese 581 planetary system, which consists of the star Gliese 581 and three confirmed planets. This system gained attention in the late 2000s and early 2010s as the subject of some of the earliest claims of potentially habitable exoplanets, but it is now known that Gliese 581c is too hot to be potentially habitable, and the planet candidates Gliese 581d and g likely do not exist. At the time of its discovery in 2009, Gliese 581e was the smallest mass exoplanet known orbiting a normal star.

### Deep-sky objects
Libra is home to one bright globular cluster, NGC 5897. It is a loose cluster, 50,000 light-years from Earth; it is fairly large and has an integrated magnitude of 9. IC 1059 is a galaxy in the constellation Libra.

## Notes
## References