Star Stars · In Boötes
Izar
Izar, ε Boötis, is a white star in Boötes: the 83rd brightest star in the night sky.
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- Constellation
- Boötes
- Designation
- ε Boötis
- Apparent magnitude
- 2.35 · 83rd brightest star in the night sky
- Spectral class
- A0
- Distance
- 203 light-years
- Highest at midnight
- late April
- Position (J2000)
- RA 14h 45m · Dec +27° 04′
A white star, around 10,000 K, like Sirius and Vega. About 46× brighter than the faintest star the eye can see. Gives off about 370 times the Sun's visible light. The light you are seeing left around 1823.
When to see it
On the night of Fri 30 Apr 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | 16:34 | 01:11 · 65° | 09:49 |
| New York EDT | 17:24 | 01:06 · 76° | 08:49 |
| Singapore GMT+8 | 19:15 | 01:17 · 64° | 07:18 |
| Sydney GMT+10 | 19:28 | 00:08 · 29° | 04:47 |
Common questions
- Can I see it from 50° north?
- Yes. It rises and sets, and at its highest it stands 67° up in the south.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 28° up in the north.
- When is the best time of year to see it?
- Around late April, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by late July it is highest in the early evening, and in late January not until the hours before dawn.
- How far away is it, and how bright?
- It is 203 light-years away, and shines at magnitude 2.35 in our sky. From that far, the Sun would be a star of magnitude 8.8: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.35 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Arcturus: Izar is 10° north-east of it, a fist at arm’s length.
Look for
From 50° north it climbs to 67°; from 35° north it climbs to 82°; from the equator it climbs to 63°; from 35° south it climbs to 28°.
Science
Izar’s surface is about 10,000 K, some 4,200 K hotter than the Sun’s 5,772 K, so its light is strongest at about 290 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 −1.6, brighter than Sirius, the brightest star in our sky.
Did you know
Against Arcturus, the brighter star the hop starts from: Arcturus looks 9.1 times as bright as Izar in our sky, but Arcturus is 37 light-years away and Izar 203 light-years, so side by side Izar would give off 3.3 times as much light as Arcturus.
Science
Izar is the 86th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Kornephoros, about 96 light-years from it; on our sky the two are 25° apart.
Look for
The Sun passes 41° south of Izar around late October, 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 17 hours a day, from 35° north about 15 and from 35° south about 9. It is 65° from the plane of the Milky Way, well away from the band.