Star Stars · In Cassiopeia
Caph
Caph, β Cassiopeiae, is a yellow-white giant in Cassiopeia: the 76th brightest star in the night sky.
Save the chart (SVG) Tactile chart (A4 SVG)
- Constellation
- Cassiopeia
- Designation
- β Cassiopeiae
- Apparent magnitude
- 2.28 · 76th brightest star in the night sky
- Spectral class
- F2III-IV
- Distance
- 54.7 light-years
- Highest at midnight
- mid September
- Position (J2000)
- RA 00h 09m · Dec +59° 09′
A yellow-white giant, around 7,200 K, like Procyon. About 49× brighter than the faintest star the eye can see. Gives off about 29 times the Sun's visible light. The light you are seeing left in 1971.
When to see it
On the night of Mon 20 Sep 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | Never sets | 01:12 · 82° | — |
| New York EDT | Never sets | 01:07 · 71° | — |
| Singapore GMT+8 | 19:09 | 01:17 · 32° | 07:25 |
| Sydney GMT+10 | 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 19° up at its lowest.
- Can I see it from 35° south?
- No. From there it never rises: you would have to travel north of 30° south before it cleared the horizon at all.
- When is the best time of year to see it?
- Around mid September, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by late December it is highest in the early evening, and in late June not until the hours before dawn.
- How far away is it, and how bright?
- It is 54.7 light-years away, and shines at magnitude 2.28 in our sky. From that far, the Sun would be a star of magnitude 5.9: one you would need a dark country sky to see at all.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.28 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Schedar: Caph is 4.9° north-west 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 31°; from 35° south it never rises.
Science
Caph’s surface is about 7,200 K, some 1,400 K hotter than the Sun’s 5,772 K, so its light is strongest at about 400 nm, 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 1.2, about as bright as Pollux looks to us.
Did you know
Against Schedar, the brighter star the hop starts from: the two look about as bright as each other in our sky; Schedar is 228 light-years away and Caph 55 light-years, so side by side Schedar would give off 18 times as much light as Caph.
Science
Caph is the 19th nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Alderamin, about 19 light-years from it; on our sky the two are 21° apart.
Look for
The Sun passes 51° south of Caph around late March, when it is highest at noon, in daylight: the weeks either side are its worst time of year. It is 3° from the plane of the Milky Way, inside the band a dark sky shows.