Star Stars · In Sagittarius
Alnasl
Alnasl, γ² Sagittarii, is an orange giant in Sagittarius: the 172nd brightest star in the night sky.
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- Constellation
- Sagittarius
- Designation
- γ² Sagittarii
- Apparent magnitude
- 2.98 · 172nd brightest star in the night sky
- Spectral class
- K0III
- Distance
- 96.9 light-years
- Highest at midnight
- mid June
- Position (J2000)
- RA 18h 06m · Dec −30° 25′
An orange giant, around 5,200 K, like Arcturus and Aldebaran. About 26× brighter than the faintest star the eye can see. Gives off about 48 times the Sun's visible light. The light you are seeing left around 1929.
When to see it
On the night of Sun 20 Jun 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | 22:23 | 01:12 · 8° | 04:01 |
| New York EDT | 21:08 | 01:06 · 19° | 05:04 |
| Singapore GMT+8 | 19:21 | 01:17 · 58° | 07:13 |
| Sydney GMT+10 | 16:36 | 00:08 · 87° | 07:40 |
Common questions
- Can I see it from 50° north?
- Only just. At its highest it is 10° above the southern horizon, so it needs a clear, flat view that way and clean air.
- Can I see it from 35° south?
- Yes, and well placed: at its highest it passes almost overhead, 85° up, above most of the air’s haze.
- When is the best time of year to see it?
- Around mid June, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by mid September it is highest in the early evening, and in late March not until the hours before dawn.
- How far away is it, and how bright?
- It is 96.9 light-years away, and shines at magnitude 2.98 in our sky. From that far, the Sun would be a star of magnitude 7.2: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.98 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Kaus Media: Alnasl is 3.3° west of it, two fingers at arm’s length.
Look for
From 50° north it barely clears the horizon, at 10°; from 35° north it climbs to 25°; from the equator it climbs to 60°; from 35° south it climbs to 85°.
Science
Alnasl’s surface is about 5,200 K, some 600 K cooler than the Sun’s 5,772 K, so its light is strongest at about 560 nm, 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 0.6, about as bright as Hadar looks to us.
Did you know
Against Kaus Media, the brighter star the hop starts from: Kaus Media looks 1.3 times as bright as Alnasl in our sky; Kaus Media is 348 light-years away and Alnasl 97 light-years, so side by side Kaus Media would give off 16 times as much light as Alnasl.
Science
Alnasl is the 52nd nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Kaus Borealis, about 21 light-years from it; on our sky the two are 7.0° apart.
Look for
The Sun passes 7.0° north of Alnasl around mid December, when it is highest at noon, in daylight: the weeks either side are its worst time of year. From 50° north it is above the horizon for about 6 hours a day, from 35° north about 9 and from 35° south about 15. It is 5° from the plane of the Milky Way, inside the band a dark sky shows.