These star-forming regions appear side-by-side in the sky, but only because they lie in the same sight line. NGC 3603 on the left is about 20,000 light years away, while the more flamboyant loops of NGC 3576 (right) are only one third as far away. Their reddish glow is the result of the ionization of hydrogen by ultraviolet light from the hot young stars with them. The more distant NGC 3603 appears brick red because much of its blue light is absorbed by dust particles in the light of sight. The closer nebula appears pinkish because more of the blue component remains in the light that reaches us.