# Zubenelgenubi (Alpha² Librae)

Zubenelgenubi (Alpha² Librae) is a star in the constellation Libra, magnitude 2.8.

**The Scorpion’s southern claw — one point of light, four stars.**

One point of light, four stars. Zubenelgenubi has a fainter partner that travels with it through space, and each of the two is itself a close pair, too tight for amateur telescopes to split. The four probably formed together, some 200 million years ago, with the stars of the Castor Moving Group — a [multiple star](https://astropilot.space/glossary/multiple-star) system.

The bright pair holds a puzzle. Its two stars have nearly equal masses, yet one spins three times faster than the other. Their spin axes may be badly misaligned, or the faster star may be the product of two stars that merged.

The name is Arabic for “the southern claw”, coined before Libra was a constellation of its own, when these stars were the claws of the Scorpion. Lying almost on the [ecliptic](https://astropilot.space/glossary/ecliptic), it can be hidden by the Moon, and very rarely by a planet: Venus covered it in 1947, and Mercury will next do so in 2052.

Zubenelgenubi (Alpha² Librae) is 76 light-years away: the light we see from it set off in 1950, 7 years before Sputnik became the first artificial satellite.

## Did you know?

- **Lost in the Sun.** From about 7 to 9 November each year the Sun itself passes in front of the star, hiding it completely.
- **The southern pan.** Its other old name, Kiffa Australis, is a partial Latin translation of the Arabic for “the southern pan” of the scales. Older texts also used Lanx Australis.
- **A fifth member?.** KU Librae, 2.6 degrees away, moves through space with the system, but its different chemistry makes it unlikely to be bound to it by gravity.

A white star of magnitude 2.8, the southern pan of the Scales, about 9 degrees south-west of Zubeneschamali. Binoculars split it into a wide pair, with a fainter, pale yellow partner nearly 4 arcminutes to the north-west.

## When and where to see it

It is best placed in the evening sky around June, when it crosses the meridian at about 10 pm local time (around midnight in May). It can be seen from everywhere south of 74°N and never sets south of 74°S.

At its highest it stands 24° up from 50°N, 39° up from 35°N, 74° up from the equator, 71° up from 35°S.

## Facts

- Type: Star
- Constellation: Libra
- Designations: Alpha² Librae, α² Lib, 9 Lib, HR 5531, HD 130841, HIP 72622
- Magnitude: 2.8
- Position: RA 14h 50.9m, Dec −16° 3′ (J2000)
- Spectral type: kA2hA5mA4IV-V
- Colour: yellow-white (B−V 0.15)
- Distance: 76 light-years
- Discovered: Known since antiquity

Open AstroPilot to see when Zubenelgenubi (Alpha² Librae) is highest tonight from your location, how easy it is with your telescope or binoculars, and an eyepiece view. https://astropilot.space/object/zubenelgenubi