Star Stars · In Ophiuchus
Saik
Saik, ζ Ophiuchi, is a blue main-sequence star in Ophiuchus: the 97th brightest star in the night sky.
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- Constellation
- Ophiuchus
- Designation
- ζ Ophiuchi
- Apparent magnitude
- 2.54 · 97th brightest star in the night sky
- Spectral class
- O9.5V
- Distance
- 366 light-years
- Highest at midnight
- late May
- Position (J2000)
- RA 16h 37m · Dec −10° 34′
A blue main-sequence star, around 31,000 K. About 38× brighter than the faintest star the eye can see. Gives off about 1,000 times the Sun's visible light. The light you are seeing left around 1660.
When to see it
On the night of Sat 29 May 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | 20:05 | 01:10 · 28° | 06:14 |
| New York EDT | 19:42 | 01:04 · 39° | 06:26 |
| Singapore GMT+8 | 19:17 | 01:15 · 78° | 07:13 |
| Sydney GMT+10 | 17:38 | 00:06 · 67° | 06:34 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 29° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 66° 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 366 light-years away, and shines at magnitude 2.54 in our sky. From that far, the Sun would be a star of magnitude 10.1: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.54 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Sabik: Saik is 9.6° north-west of it, a fist at arm’s length.
Look for
From 50° north it climbs to 29°; from 35° north it climbs to 44°; from the equator it climbs to 79°; from 35° south it climbs to 66°.
Science
Saik’s surface is about 31,000 K, some 25,200 K hotter than the Sun’s 5,772 K, so its light is strongest at about 90 nm, in the ultraviolet, past the violet end of what the eye can see, 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 −2.7, brighter than Sirius, the brightest star in our sky.
Did you know
Against Sabik, the brighter star the hop starts from: the two look about as bright as each other in our sky; Sabik is 88 light-years away and Saik 366 light-years, so side by side Saik would give off 16 times as much light as Sabik.
Science
Saik is the 107th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Acrab, about 89 light-years from it; on our sky the two are 12° apart.
Look for
The Sun passes 11° south of Saik 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 10 hours a day, from 35° north about 11 and from 35° south about 13. It is 24° from the plane of the Milky Way.