Deneb
What is Deneb?
Stars· Distance ~2,600 ly · size 200× Sun. Tail star of the Swan and one corner of the Summer Triangle. It is among the most distant stars visible to the naked eye, yet still shines at first magnitude because it pours out about 200,000 times the Sun's light.
📍 Visible from where you are right now — computed in your browser
bearing · altitude · rise time · best time tonight
Where Deneb is in your sky right now: https://nowsky.org/solar/sky?sel=deneb — location and time set automatically, no login.
Distance and spectral type
Deneb is about 1,412 light-years away, a white supergiant (spectral type A2Ia), in the constellation Cassiopeia. Its apparent magnitude is 1.3, visible to the naked eye.
Stellar figures
| Distance | ~2,600 ly |
|---|---|
| Magnitude | 1.25 — Cygnus's brightest |
| Luminosity | ~200,000× Sun |
| Constellation | Cygnus |
Figures are representative approximations. Source: compiled from NASA and IAU public data.
Behind the name
Arabic "tail of the hen". One of the most luminous stars known — first magnitude from ~3,000 ly away.
Frequently asked
- How far is Deneb from Earth?
- ~2,600 ly.
- How bright is Deneb (apparent magnitude)?
- 1.25 — Cygnus's brightest.
- Which constellation is Deneb in?
- Cassiopeia.
- Where is Deneb in the sky right now?
- Open the sky view for your location and time and it shows the position in the sky right now.
Why Deneb's distance is so hard to measure
Distances to nearby stars are measured by parallax — the tiny shift of a star against the background as Earth circles the Sun. Deneb is so far that the shift is about two thousandths of an arcsecond, and the Hipparcos satellite's values ranged from 1,400 to 3,200 light-years. The "about 2,600 light-years" in this index is a middle value with an error of hundreds of light-years; bright stars also saturate detectors, which makes their positions harder to fix.
Double the distance and the luminosity quadruples, so Deneb's luminosity runs from 50,000 to 200,000 Suns depending on the source, and its diameter from 100 to 200 solar. What is certain is that it is among the most distant naked-eye stars, with roughly twenty solar masses and a supernova ahead within a few million years. The final Gaia data are expected to pin its distance to within 10 percent for the first time.
The star in depth
Deneb is the blue-white supergiant marking the tail of Cygnus — the name literally means 'tail' in Arabic. Roughly 200 times the Sun's diameter and about 200,000 times its luminosity, it ranks among the most luminous stars in the Milky Way. Distance estimates scatter between about 1,500 and 2,600 light-years, but by any value it is by far the most distant first-magnitude star you can see without optics.
With Vega and Altair it forms the Summer Triangle. Deneb looks the faintest of the three, yet it is easily the most powerful: Vega sits 25 light-years away and Altair 17, while Deneb is nearly a hundred times farther. At about 19 solar masses it is destined to end as a supernova within a few million years.
On northern summer nights the Milky Way runs lengthwise through Cygnus, and Deneb sits at its upper end near the zenith. Select it in the Sky view to see the Swan's wings and tail traced out, or drop it onto the size ladder next to the Sun to feel that 200-to-1 size gap directly.
Related
Figures are representative approximations. Simulated positions use J2000 mean elements.