Physical Size
A scroll-driven journey through the scale of the universe, from subatomic structures to the largest known cosmic systems.
Cygnus X-1
NGC 4395 Black Hole
Stellar black hole
Cygnus X-1
The first widely accepted black hole, pulling gas from a massive star.
Cygnus X-1 was the first cosmic object widely accepted as a black hole. It blazes in X-rays because the black hole is stripping hot gas from a massive blue supergiant companion and funneling it into a compact accretion flow.
- event horizon diameter
- 120 km
- Mass
- ~21 solar masses
- Age
- ~5 million years
- Orbits
- Cygnus X-1 binary system
Image: scaleofspace.org · CC BY-NC 4.0