Star Stars · In Aquarius
Sadalsuud
Sadalsuud, β Aquarii, is a yellow supergiant in Aquarius: the 162nd brightest star in the night sky.
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- Constellation
- Aquarius
- Designation
- β Aquarii
- Apparent magnitude
- 2.90 · 162nd brightest star in the night sky
- Spectral class
- G0Ib
- Distance
- 537 light-years
- Highest at midnight
- mid August
- Position (J2000)
- RA 21h 32m · Dec −05° 34′
A yellow supergiant, around 6,000 K, like the Sun. About 28× brighter than the faintest star the eye can see. Gives off about 1,600 times the Sun's visible light. The light you are seeing left around 1489.
When to see it
On the night of Wed 11 Aug 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | 19:41 | 01:12 · 33° | 06:44 |
| New York EDT | 19:27 | 01:07 · 44° | 06:47 |
| Singapore GMT+8 | 19:19 | 01:17 · 83° | 07:16 |
| Sydney GMT+10 | 17:55 | 00:08 · 62° | 06:22 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 34° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 61° up in the north.
- When is the best time of year to see it?
- Around mid August, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by mid November it is highest in the early evening, and in mid May not until the hours before dawn.
- How far away is it, and how bright?
- It is 537 light-years away, and shines at magnitude 2.90 in our sky. From that far, the Sun would be a star of magnitude 10.9: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.90 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Deneb Algedi: Sadalsuud is 11° north of it, a fist at arm’s length.
Look for
From 50° north it climbs to 34°; from 35° north it climbs to 49°; from the equator it climbs to 84°; from 35° south it climbs to 61°.
Science
Sadalsuud’s surface is about 6,000 K, some 200 K hotter than the Sun’s 5,772 K, so its light is strongest at about 480 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 −3.2, brighter than Sirius, the brightest star in our sky.
Did you know
Against Deneb Algedi, the brighter star the hop starts from: the two look about as bright as each other in our sky; Deneb Algedi is 39 light-years away and Sadalsuud 537 light-years, so side by side Sadalsuud would give off 180 times as much light as Deneb Algedi.
Science
Sadalsuud is the 132nd nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Sadalmelik, about 94 light-years from it; on our sky the two are 10° apart.
Look for
The Sun passes 8.6° south of Sadalsuud around early February, 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 11 hours a day, from 35° north about 11 and from 35° south about 12. It is 38° from the plane of the Milky Way.