Star · B0I
Cygnus X-1
Cygnus X-1 is a supergiant star of spectral type B0I in the constellation Cygnus, 7,348 light-years from the Sun.
| Other names | HIP 98298 |
|---|---|
| Constellation | Cygnus |
| Distance | 7,348 light-years (2,253 pc) |
| Apparent magnitude | magnitude 8.84 |
| Absolute magnitude | magnitude −2.92 |
| Spectral type | B0I |
| Surface temperature | 5,500 K |
| Luminosity | 1,460 L☉ |
| Radius | 42 R☉ |
| Mass | 7.28 M☉ (estimated) |
| Right ascension (J2000) | 19h 58m 21.7s |
| Declination (J2000) | +35° 12′ 06″ |
| Space velocity (relative to the Sun) | 78.8 km/s |
In the sky
Too faint for the naked eye (magnitude 8.84); binoculars will find it. Visible from the whole Northern Hemisphere and south to latitude 55° S. North of latitude 55° N it never sets. It stands highest at midnight in July, the best time to observe it.
Through a telescope from Earth
Light's journey
The light you see tonight set out 7,348 years ago. At that time the first farming villages were being founded; there was no writing yet. At the speed of Voyager 1, the fastest craft leaving the Solar System (16.9 km per second), the trip would take 130 million years.
The Sun seen from there
From a planet around Cygnus X-1, the Sun would look like a star of magnitude 16.59, in the direction where our sky has the constellation Puppis. It would be invisible to the naked eye.
Position, brightness and colour from the HYG / AT-HYG catalogue; temperature, luminosity, radius and mass are approximate values computed from these observations.