How to Find the Libra Constellation in the Night Sky

Northern hemisphere summer constellations.
Look for Libra in the late spring and summer. This Northern hemisphere chart shows the summer skies, looking south.

Carolyn Collins Petersen

The star pattern we call Libra is a small but distinct constellation next to the constellation Virgo in the evening sky. It looks very much like a lopsided diamond or crooked box and is visible in the northern hemisphere between April and July. Libra is most visible directly overhead at midnight in June.

Finding the Libra Constellation

Libra constellation
The constellation Libra is next to the constellation Virgo in the evening skies from March to September.

Carolyn Collins Petersen 

Finding Libra is very easy. First, look for the Big Dipper, which is part of the constellation Ursa Major. Follow the curve of the handle down to the bright star Arcturus in the nearby constellation Boötes. From there, look down to Virgo. Libra is right next to Virgo, not far from the star Spica.

Libra is visible from most points on the planet, although for viewers in the far north, it disappears into the bright sunny skies of the Arctic night for much of the summer. Observers far south may only catch a glimpse of it in their far north sky.

The Story of Libra

Like so many constellations, the stars that comprise Libra have been recognized in the sky as a distinct set of star patterns since antiquity. In Ancient Egypt, the constellation was seen as having the shape of a boat. The Babylonians interpreted its shape as that of a scale, and they ascribed the virtues of truth and justice to it. Ancient Greek and Roman stargazers also identified Libra as having the shape of a scale.

Libra was one of the 48 constellations of antiquity, joined in later centuries by other star patterns. Today, there are 88 recognized constellation regions in the sky.

The Stars of the Constellation Libra

constellation libra star chart
The IAU official chart of stars in the constellation Libra.

IAU

The constellation shape of Libra contains four bright "box" stars and a set of three others attached. Libra lies in in an odd-shaped region delineated by boundaries set by the International Astronomical Union. These were made by international agreement and allow astronomers to use common references for stars and other objects in all areas of the sky. Within that region, Libra has 83 stars.

Each star has a Greek letter next to it in the official star chart. The alpha (α) denotes the brightest star, beta (β) the second-brightest star, and so on. The brightest star in Libra is α Librae. Its common name is Zubenelgenubi, meaning "the Southern Claw" in Arabic. It is a double star and was once thought to be part of nearby Scorpius. This star pair is fairly close to Earth, at a distance of 77 light-years. Astronomers know now that one of the pair is also a binary star.

The second-brightest star in the constellation Libra is β Librae, also known as Zubeneschamali. The name comes from the Arabic for "The Northern Claw." β Librae was also once thought to be part of Scorpius before being put into Libra. Many stars in the constellation are double stars and some are variable stars (which means they vary in brightness). Here's a list of the best-known:

  • δ Librae: an eclipsing variable star
  • μ Librae: a double star that can be seen through medium-size telescopes

Astronomers have been studying some of the stars in Libra in the search for extrasolar planets. So far, they have found planets around the red dwarf star Gliese 581. Gliese 581 appears to have three confirmed planets, and may have several others. The whole system is fairly close to Earth, at a distance of 20 light-years, and has been found to have a cometary belt similar to our solar system's Kuiper Belt and Oört Cloud.

Deep Sky Objects in the Constellation Libra

Libra constellation and NGC 5897
Use this chart to spy out the location of Libra's only globular cluster.

 Carolyn Collins Petersen

The constellation Libra has one key deep sky object: a globular cluster called NGC 5897.

Globular clusters are a distinct type of star cluster that contain hundreds, thousands, and sometimes millions of stars, all tightly bound together by gravity. NGC 5897 orbits the core of the Milky Way and lies about 24,000 light-years away.

Astronomers study these clusters, and particularly the metal "content" of their stars, to understand more about them. The stars of NGC 5897 are very metal-poor, meaning that they formed at a time in the universe when elements heavier than hydrogen and helium were not very abundant. That means the cluster is very old, possibly older than our galaxy (or at least close to the same age of about 10 billion years).