NGC 6559

NGC 6559 is a nebula about 5000 light years away in the constellation Sagittarius.
NGC 6559 includes reddish emission nebula, bluish reflection nebula and dark clouds. The reddish emission nebulae are composed of hydrogen, which emits light on the Hα line. The bluish reflection nebulae are illuminated by young stars. The dark clouds are composed of cold molecules and dust.
The nebula was discovered on July 1, 1826 by astronomer John Herschel with his 48-cm telescope.