Star Stars · In Taurus
Tianguan
Tianguan, ζ Tauri, is a blue-white giant in Taurus: the 170th brightest star in the night sky.
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- Constellation
- Taurus
- Designation
- ζ Tauri
- Apparent magnitude
- 2.97 · 170th brightest star in the night sky
- Spectral class
- B4IIIp
- Distance
- 445 light-years
- Highest at midnight
- mid December
- Position (J2000)
- RA 05h 38m · Dec +21° 09′
A blue-white giant, around 22,000 K, like Rigel and Spica. About 26× 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 1581.
When to see it
On the night of Sun 13 Dec 2026, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT | 16:13 | 00:09 · 60° | 08:04 |
| New York EST | 16:47 | 00:03 · 70° | 07:20 |
| Singapore GMT+8 | 19:13 | 01:14 · 70° | 07:15 |
| Sydney GMT+11 | 20:06 | 01:05 · 35° | 06:04 |
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 mid December, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by mid March it is highest in the early evening, and in mid September not until the hours before dawn.
- How far away is it, and how bright?
- It is 445 light-years away, and shines at magnitude 2.97 in our sky. From that far, the Sun would be a star of magnitude 10.5: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.97 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Elnath: Tianguan is 7.9° south of it, a fist 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
Tianguan’s surface is about 22,000 K, some 16,200 K hotter than the Sun’s 5,772 K, so its light is strongest at about 130 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 Elnath, the brighter star the hop starts from: Elnath looks 3.4 times as bright as Tianguan in our sky, but Elnath is 134 light-years away and Tianguan 445 light-years, so side by side Tianguan would give off 3.3 times as much light as Elnath.
Science
Tianguan is the 121st nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Betelgeuse, about 130 light-years from it; on our sky the two are 14° apart.
Look for
Tianguan lies 2.2° south of the ecliptic, close enough to the Sun’s path that the Moon can pass in front of it and the planets pass near it. The Sun goes by around mid June, and for weeks either side it is lost in the glare. 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 6° from the plane of the Milky Way, inside the band a dark sky shows.