Star Stars · In Lupus
Uridim
Uridim, α Lupi, is a blue-white giant in Lupus: the 80th brightest star in the night sky.
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- Constellation
- Lupus
- Designation
- α Lupi
- Apparent magnitude
- 2.30 · 80th brightest star in the night sky
- Spectral class
- B1.5III
- Distance
- 465 light-years
- Highest at midnight
- late April
- Position (J2000)
- RA 14h 42m · Dec −47° 23′
A blue-white giant, around 27,000 K, like Rigel and Spica. About 48× brighter than the faintest star the eye can see. Gives off about 2,000 times the Sun's visible light. The light you are seeing left around 1561.
When to see it
On the night of Fri 30 Apr 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | Never rises | ||
| New York EDT | 23:44 | 01:04 · 2° | 02:24 |
| Singapore GMT+8 | 19:21 | 01:14 · 41° | 07:07 |
| Sydney GMT+10 | 14:58 | 00:05 · 76° | 09:12 |
Common questions
- Can I see it from 50° north?
- No. From there it never rises: you would have to travel south of 42° north before it cleared the horizon at all.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 78° up in the south.
- When is the best time of year to see it?
- Around late April, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by late July 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 465 light-years away, and shines at magnitude 2.30 in our sky. From that far, the Sun would be a star of magnitude 10.6: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.30 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Menkent: Uridim is 13° south-east of it, a fist and a half at arm’s length.
Look for
From 50° north it never rises; from 35° north it barely clears the horizon, at 8°; from the equator it climbs to 43°; from 35° south it climbs to 78°.
Science
Uridim’s surface is about 27,000 K, some 21,200 K hotter than the Sun’s 5,772 K, so its light is strongest at about 110 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 −3.5, brighter than Sirius, the brightest star in our sky.
Did you know
Against Menkent, the brighter star the hop starts from: the two look about as bright as each other in our sky; Menkent is 59 light-years away and Uridim 465 light-years, so side by side Uridim would give off 50 times as much light as Menkent.
Science
Uridim is the 122nd nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is KeKouan, about 90 light-years from it; on our sky the two are 5.2° apart.
Look for
The Sun passes 30° north of Uridim around late October, when it is highest at noon, in daylight: the weeks either side are its worst time of year. From 35° north it is above the horizon for about 5 hours a day and from 35° south about 19. It is 11° from the plane of the Milky Way.