Credit: NASA/CXC/SAO

About a decade after its discovery in 1964, a combination of X-ray and optical observations led to the conclusion that Cygnus X-1 was a black hole - the first such identification. The Cygnus X-1 system consists of a black hole with a mass about 10 times that of the Sun in a close orbit with a blue supergiant star with a mass of about 20 Suns. Because of its brightness and close proximity, Cygnus X-1 continues to attract the interest of scientists seeking to understand the nature of black holes and how they affect their environment.

Provider: Chandra X-ray Observatory

Image Source: http://chandra.harvard.edu/photo/2009/cygx1/

Curator: Chandra X-ray Observatory, Cambrdige, MA, USA

Image Use Policy: http://chandra.harvard.edu/photo/image_use.html