Libra
What is Libra?
Constellations· Early summer evenings (N) · between Spica and Antares. The only inanimate object among the zodiac signs. Its star names mean "southern claw" and "northern claw" in Arabic, because these stars were the claws of Scorpius before Roman times. Zubeneschamali is often described as the only naked-eye star with a greenish tint.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Libra is in your sky right now: https://nowsky.org/solar/sky?sel=con:Libra — location and time set automatically, no login.
Stars of the figure
| Star | Magnitude |
|---|---|
| Zubeneschamali | 2.6 |
| Zubenelgenubi | 2.8 |
| Zubenelhakrabi | 3.9 |
The 3 brightest of the 4 stars used in the figure (4 lines). Lower magnitude means brighter.
Deep-sky objects near this constellation
Constellation basics
| Season | late spring to early summer, May–July |
|---|---|
| Brightest star | Zubeneschamali (2.6) |
| How to find | a tilted quadrilateral midway between Spica and Antares |
| Area rank | 29th of 88 |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Frequently asked
- When can I see Libra?
- late spring to early summer, May–July.
- How do I find Libra?
- a tilted quadrilateral midway between Spica and Antares.
- What is the brightest star in Libra?
- Zubeneschamali, magnitude 2.6.
- Where is Libra in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
Gliese 581 — the stage of the habitable-planet debate
Libra holds the red dwarf Gliese 581, 20 light-years away. In 2007 its planet 581c was announced as the first exoplanet at a temperature where life could exist and made news around the world, and in 2010 581g was put forward as a stronger candidate. Later precise analysis judged 581g to be a signal produced by the star's own rotation, denying its existence, and 581c came to be seen as hot like Venus.
The debate became a standard example of how hard exoplanet hunting is: how difficult it is to separate a wobble of about one metre per second in radial velocity from activity on the star's surface, and how the word habitable is not settled by temperature alone. This dim star in Libra cannot be seen by eye, but it is where the methods of exoplanet research were sharpened.
The constellation in depth
Libra began as the two claws of the Scorpion. In Roman times the stars were separated into the scales held by the goddess of justice, and since the autumn equinox then fell here — day and night in balance — the symbolism stuck. Libra is thus paired with Virgo, seen as Astraea, the goddess of justice. Even today its two brightest stars keep names that recall the scorpion rather than the scales.
Zubenelgenubi is a wide double star that binoculars split easily, and Zubeneschamali has been recorded since antiquity as a green-tinted star. A star cannot physically shine green, so the effect is usually called an illusion, yet observers still argue about it. The constellation also holds Gliese 581, a red dwarf that was an early target in the exoplanet hunt.
On early-summer evenings look south between Spica to the west and Antares to the east: four stars in a tilted quadrilateral form the scales. With no bright stars, city skies show only the two "claw" stars. In the Sky view a June night puts Libra just west of Scorpius. Look for it around midnight in May or in the early evening in July, when it stands highest above the southern horizon.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.