Star Stars · In Libra
Zubenelgenubi
Zubenelgenubi, α² Librae, is a white subgiant in Libra: the 126th brightest star in the night sky.
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- Constellation
- Libra
- Designation
- α² Librae
- Apparent magnitude
- 2.75 · 126th brightest star in the night sky
- Spectral class
- A3IV
- Distance
- 75.8 light-years
- Highest at midnight
- early May
- Position (J2000)
- RA 14h 51m · Dec −16° 03′
A white subgiant, around 9,300 K, like Sirius and Vega. About 32× brighter than the faintest star the eye can see. Gives off about 36 times the Sun's visible light. The light you are seeing left in 1950.
When to see it
On the night of Sun 2 May 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | 20:36 | 01:10 · 22° | 05:44 |
| New York EDT | 20:03 | 01:04 · 33° | 06:06 |
| Singapore GMT+8 | 19:18 | 01:15 · 72° | 07:12 |
| Sydney GMT+10 | 17:22 | 00:06 · 72° | 06:50 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 24° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 71° up in the north.
- When is the best time of year to see it?
- Around early May, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by early August it is highest in the early evening, and in late January not until the hours before dawn.
- How far away is it, and how bright?
- It is 75.8 light-years away, and shines at magnitude 2.75 in our sky. From that far, the Sun would be a star of magnitude 6.6: one you would need a dark country sky to see at all.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.75 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Zubeneschamali: Zubenelgenubi is 9.2° south-west of it, a fist at arm’s length.
Look for
From 50° north it climbs to 24°; from 35° north it climbs to 39°; from the equator it climbs to 74°; from 35° south it climbs to 71°.
Science
Zubenelgenubi’s surface is about 9,300 K, some 3,500 K hotter than the Sun’s 5,772 K, so its light is strongest at about 310 nm, in the ultraviolet, past the violet end of what the eye can see, where the Sun’s is strongest at 500 nm. Moved to 33 light-years, the distance astronomers compare stars at, it would shine at magnitude 0.9, about as bright as Aldebaran looks to us.
Did you know
Against Zubeneschamali, the brighter star the hop starts from: the two look about as bright as each other in our sky; Zubeneschamali is 185 light-years away and Zubenelgenubi 76 light-years, so side by side Zubeneschamali would give off 6.8 times as much light as Zubenelgenubi.
Science
Zubenelgenubi is the 31st nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Menkent, about 31 light-years from it; on our sky the two are 23° apart.
Look for
Zubenelgenubi lies 0.3° north of the ecliptic, close enough to the Sun’s path that the Moon can pass in front of it and the planets pass near it. The Sun goes by around late October, and for weeks either side it is lost in the glare. From 50° north it is above the horizon for about 9 hours a day, from 35° north about 10 and from 35° south about 14. It is 38° from the plane of the Milky Way.