(catalog number NGC 7000), ionized-hydrogen region in the constellation Cygnus. The nebula is a cloud of interstellar gas ionized from within by young, hot stars. Interstellar dust particles in part of this cloud absorb the light emitted by recombining atoms. The shape of the nebula roughly resembles that of North America, with the dusty region being shaped like the Gulf of Mexico. The North American Nebula is approximately 520 parsecs (1,700 light-years) from the Sun. It has a diameter of about 30 parsecs (100 light-years) and a total mass equal to about 4,000 solar masses.