Star Stars · In Hydra
Alphard
Alphard, α Hydrae, is an orange giant in Hydra: the 50th brightest star in the night sky.
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- Constellation
- Hydra
- Designation
- α Hydrae
- Apparent magnitude
- 1.99 · 50th brightest star in the night sky
- Spectral class
- K3III
- Distance
- 180 light-years
- Highest at midnight
- early February
- Position (J2000)
- RA 09h 28m · Dec −08° 40′
An orange giant, around 4,800 K, like Arcturus and Aldebaran. About 64× brighter than the faintest star the eye can see. Gives off about 410 times the Sun's visible light. The light you are seeing left around 1846.
When to see it
On the night of Tue 9 Feb 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT | 18:55 | 00:10 · 30° | 05:24 |
| New York EST | 18:36 | 00:04 · 41° | 05:33 |
| Singapore GMT+8 | 19:17 | 01:15 · 80° | 07:13 |
| Sydney GMT+11 | 18:43 | 01:06 · 65° | 07:29 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 31° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 64° up in the north.
- When is the best time of year to see it?
- Around early February, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by mid May it is highest in the early evening, and in early November not until the hours before dawn.
- How far away is it, and how bright?
- It is 180 light-years away, and shines at magnitude 1.99 in our sky. From that far, the Sun would be a star of magnitude 8.5: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 1.99 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Regulus: Alphard is 23° south-west of it, a spread hand at arm’s length.
Look for
From 50° north it climbs to 31°; from 35° north it climbs to 46°; from the equator it climbs to 81°; from 35° south it climbs to 64°.
Science
Alphard’s surface is about 4,800 K, some 1,000 K cooler than the Sun’s 5,772 K, so its light is strongest at about 600 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 −1.7, brighter than Sirius, the brightest star in our sky.
Did you know
Against Regulus, the brighter star the hop starts from: Regulus looks 1.8 times as bright as Alphard in our sky, but Regulus is 79 light-years away and Alphard 180 light-years, so side by side Alphard would give off 2.9 times as much light as Regulus.
Science
Alphard is the 81st nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Algieba, about 97 light-years from it; on our sky the two are 31° apart.
Look for
The Sun passes 22° north of Alphard around early August, 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 13. It is 29° from the plane of the Milky Way.