Star Stars · In Triangulum Australe
Atria
Atria, α Trianguli Australis, is an orange bright giant in Triangulum Australe: the 44th brightest star in the night sky.
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- Constellation
- Triangulum Australe
- Designation
- α Trianguli Australis
- Apparent magnitude
- 1.91 · 44th brightest star in the night sky
- Spectral class
- K2IIb-IIIa
- Distance
- 391 light-years
- Highest at midnight
- early June
- Position (J2000)
- RA 16h 49m · Dec −69° 02′
An orange bright giant, around 4,900 K, like Arcturus and Aldebaran. About 69× brighter than the faintest star the eye can see. Gives off about 2,100 times the Sun's visible light. The light you are seeing left around 1635.
When to see it
On the night of Tue 1 Jun 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 | Never rises | ||
| Singapore GMT+8 | 19:31 | 01:16 · 20° | 07:01 |
| Sydney GMT+10 | Never sets | 00:07 · 55° | — |
Common questions
- Can I see it from 50° north?
- No. From there it never rises: you would have to travel south of 20° north before it cleared the horizon at all.
- Can I see it from 35° south?
- Yes, on any clear night of the year. From there it never sets: it is circumpolar, circling the pole and still 14° up at its lowest.
- When is the best time of year to see it?
- Around early June, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by late August it is highest in the early evening, and in early March not until the hours before dawn.
- How far away is it, and how bright?
- It is 391 light-years away, and shines at magnitude 1.91 in our sky. From that far, the Sun would be a star of magnitude 10.2: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 1.91 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Toliman: Atria is 16° south-east of it, a fist and a half at arm’s length.
Look for
From 50° north and 35° north it never rises; from the equator it climbs to 21°; from 35° south it is circumpolar and never sets.
Science
Atria’s surface is about 4,900 K, some 900 K cooler than the Sun’s 5,772 K, so its light is strongest at about 590 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 −3.5, brighter than Sirius, the brightest star in our sky.
Did you know
Against Toliman, the brighter star the hop starts from: Toliman looks 1.7 times as bright as Atria in our sky, but Toliman is 4 light-years away and Atria 391 light-years, so side by side Atria would give off 4,900 times as much light as Toliman.
Science
Atria is the 111th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Hadar, about 130 light-years from it; on our sky the two are 19° apart.
Look for
The Sun passes 46° north of Atria around late November, when it is highest at noon, in daylight: the weeks either side are its worst time of year. It is 15° from the plane of the Milky Way.