Star Stars · In Cassiopeia
Ruchbah
Ruchbah, δ Cassiopeiae, is a white main-sequence star in Cassiopeia: the 110th brightest star in the night sky.
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- Constellation
- Cassiopeia
- Designation
- δ Cassiopeiae
- Apparent magnitude
- 2.66 · 110th brightest star in the night sky
- Spectral class
- A5Vv SB
- Distance
- 99.4 light-years
- Highest at midnight
- early October
- Position (J2000)
- RA 01h 26m · Dec +60° 14′
A white main-sequence star, around 8,800 K, like Sirius and Vega. About 34× brighter than the faintest star the eye can see. Gives off about 67 times the Sun's visible light. The light you are seeing left around 1927.
When to see it
On the night of Sun 10 Oct 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | Never sets | 01:10 · 81° | — |
| New York EDT | Never sets | 01:05 · 70° | — |
| Singapore GMT+8 | 19:07 | 01:16 · 31° | 07:24 |
| Sydney GMT+11 | Never rises | ||
Common questions
- Can I see it from 50° north?
- Yes, on any clear night of the year. From there it never sets: it is circumpolar, circling the pole and still 20° up at its lowest.
- Can I see it from 35° south?
- No. From there it never rises: you would have to travel north of 29° south before it cleared the horizon at all.
- When is the best time of year to see it?
- Around early October, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by early January it is highest in the early evening, and in mid July not until the hours before dawn.
- How far away is it, and how bright?
- It is 99.4 light-years away, and shines at magnitude 2.66 in our sky. From that far, the Sun would be a star of magnitude 7.2: too faint for the eye, a target for binoculars.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.66 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Cih: Ruchbah is 3.6° east of it, three fingers at arm’s length.
Look for
From 50° north and 35° north it is circumpolar and never sets; from the equator it climbs to 30°; from 35° south it never rises.
Science
Ruchbah’s surface is about 8,800 K, some 3,000 K hotter than the Sun’s 5,772 K, so its light is strongest at about 330 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 0.2, about as bright as Rigel looks to us.
Did you know
Against Cih, the brighter star the hop starts from: Cih looks 1.6 times as bright as Ruchbah in our sky; Cih is 549 light-years away and Ruchbah 99 light-years, so side by side Cih would give off 49 times as much light as Ruchbah.
Science
Ruchbah is the 54th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Algol, about 42 light-years from it; on our sky the two are 25° apart.
Look for
The Sun passes 46° south of Ruchbah around early April, when it is highest at noon, in daylight: the weeks either side are its worst time of year. It is 2° from the plane of the Milky Way, inside the band a dark sky shows.