Star Stars · In Hercules
Kornephoros
Kornephoros, β Herculis, is a yellow giant in Hercules: the 129th brightest star in the night sky.
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- Constellation
- Hercules
- Designation
- β Herculis
- Apparent magnitude
- 2.78 · 129th brightest star in the night sky
- Spectral class
- G8III
- Distance
- 139 light-years
- Highest at midnight
- late May
- Position (J2000)
- RA 16h 30m · Dec +21° 29′
A yellow giant, around 5,400 K, like the Sun. About 31× brighter than the faintest star the eye can see. Gives off about 120 times the Sun's visible light. The light you are seeing left around 1887.
When to see it
On the night of Thu 27 May 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | 17:13 | 01:10 · 60° | 09:07 |
| New York EDT | 17:47 | 01:05 · 71° | 08:23 |
| Singapore GMT+8 | 19:14 | 01:15 · 70° | 07:17 |
| Sydney GMT+10 | 19:08 | 00:06 · 35° | 05:05 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 61° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 34° up in the north.
- When is the best time of year to see it?
- Around late May, 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 late February not until the hours before dawn.
- How far away is it, and how bright?
- It is 139 light-years away, and shines at magnitude 2.78 in our sky. From that far, the Sun would be a star of magnitude 8.0: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.78 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Alphecca: Kornephoros is 14° east of it, a fist and a half at arm’s length.
Look for
From 50° north it climbs to 61°; from 35° north it climbs to 76°; from the equator it climbs to 69°; from 35° south it climbs to 34°.
Science
Kornephoros’s surface is about 5,400 K, some 400 K cooler than the Sun’s 5,772 K, so its light is strongest at about 540 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 −0.4, about as bright as Rigil Kentaurus looks to us.
Did you know
Against Alphecca, the brighter star the hop starts from: Alphecca looks 1.7 times as bright as Kornephoros in our sky, but Alphecca is 75 light-years away and Kornephoros 139 light-years, so side by side Kornephoros would give off 2.1 times as much light as Alphecca.
Science
Kornephoros is the 67th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Alphecca, about 69 light-years from it; on our sky the two are 14° apart.
Look for
The Sun passes 43° south of Kornephoros around late November, 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 16 hours a day, from 35° north about 14 and from 35° south about 10. It is 40° from the plane of the Milky Way.