Star profile
Theta Cepheus
What is Theta Cepheus
Theta Cephei is a white A7-type star about 136 light-years away, a spectroscopic binary betrayed by the periodic wobble of its light. It belongs to Cepheus, the mythical king and husband of Cassiopeia, and forms part of the Celestial Hook of Chinese astronomy, a faint line traced through the constellation. Hard to spot from a city, in a dark sky it emerges with quiet poise.
Where it is and when to see it
Theta Cepheus lies in the northern celestial hemisphere. It is visible to the naked eye under a dark sky. Its best month of the year is September, when it culminates around midnight.
- From London it never sets and culminates about 79° up.
- From New York it never sets and culminates about 68° up.
- From Sydney it never rises above the horizon.
It can be seen from anywhere north of 27° S.
It ranks no. 9 in brightness among the 95 stars of Cepheus in our catalogue. To find it, start from Alderamin, the brightest: it lies about 6° away (a fist at arm's length covers about 10°).
The light you see today left it about 140 years ago.
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Astronomical data for Theta Cepheus
- Constellation
- Cepheus
- Apparent magnitude
- 4.21
- Distance
- 136.5 light years
- Coordinates (J2000)
- RA 307.395° · Dec 62.994°
- Catalogue
- HIP 101093 · HD 195725
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Other stars in Cepheus
Cepheus has 95 stars in Stelvia's catalogue. Here are a few of them.
- AlderaminAlpha Cepheus2.45
- ErraiGamma Cepheus3.21
- AlfirkBeta Cepheus3.23
- Iota Cepheus3.50
- Delta Cepheus4.07
- Epsilon Cepheus4.18
- Mu Cepheus4.23
- HIP 53724.24