Star Stars · In Cygnus
Sadr
Sadr, γ Cygni, is a yellow-white supergiant in Cygnus: the 72nd brightest star in the night sky.
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- Constellation
- Cygnus
- Designation
- γ Cygni
- Apparent magnitude
- 2.23 · 72nd brightest star in the night sky
- Spectral class
- F8Ib
- Distance
- 1,832 light-years
- Highest at midnight
- late July
- Position (J2000)
- RA 20h 22m · Dec +40° 15′
A yellow-white supergiant, around 6,300 K, like Procyon. About 51× brighter than the faintest star the eye can see. Gives off about 34,000 times the Sun's visible light. The light you are seeing left around 194.
When to see it
On the night of Sun 25 Jul 2027, when it is highest around midnight, on each city’s own clock:
| From | Rises | Highest | Sets |
|---|---|---|---|
| London GMT+1 | Never sets | 01:09 · 79° | — |
| New York EDT | 15:58 | 01:04 · 90° | 10:10 |
| Singapore GMT+8 | 19:11 | 01:15 · 51° | 07:18 |
| Sydney GMT+10 | 20:25 | 00:06 · 16° | 03:46 |
Common questions
- Can I see it from 50° north?
- Yes, on any clear night of the year — it is circumpolar from there and never quite sets, though at its lowest it skims the horizon, where trees and haze will hide it.
- Can I see it from 35° south?
- Yes. It rises and sets, and at its highest it stands 15° up in the north.
- When is the best time of year to see it?
- Around late July, when it stands opposite the Sun and is highest at midnight. It comes round about two hours earlier each month, so by late October it is highest in the early evening, and in late April not until the hours before dawn.
- How far away is it, and how bright?
- It is 1,832 light-years away, and shines at magnitude 2.23 in our sky. From that far, the Sun would be a star of magnitude 13.6: too faint for anything less than a telescope.
- Naked eye, binoculars or telescope?
- The naked eye, even from a city: at magnitude 2.23 it is brighter than the faintest stars a city sky still shows, about magnitude 4.5.
Look for
Start from Deneb: Sadr is 6.1° south-west of it, three fingers at arm’s length.
Look for
From 50° north it is circumpolar and never sets; from 35° north it climbs to 85°; from the equator it climbs to 50°; from 35° south it climbs to 15°.
Science
Sadr’s surface is about 6,300 K, some 500 K hotter than the Sun’s 5,772 K, so its light is strongest at about 460 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 −6.5, brighter than Sirius, the brightest star in our sky.
Did you know
Against Deneb, the brighter star the hop starts from: Deneb looks 2.5 times as bright as Sadr in our sky; Deneb is 1,412 light-years away and Sadr 1,832 light-years, so side by side Deneb would give off 1.5 times as much light as Sadr.
Science
Sadr is the 152nd nearest to us of the 156 stars on these pages with a measured distance. Its nearest neighbour among them in space is Deneb, about 450 light-years from it; on our sky the two are 6.1° apart.
Look for
The Sun passes 57° south of Sadr around late January, when it is highest at noon, in daylight: the weeks either side are its worst time of year. From 35° north it is above the horizon for about 17 hours a day and from 35° south about 7. It is 2° from the plane of the Milky Way, inside the band a dark sky shows.