... Part of a larger emission nebula with a distinctive outline popularly called The North America Nebula, the cosmic ridge spans about 20 light-years. ... Galaxy and Cluster Create Four Images of Distant Supernova . ... The center of our Milky Way Galaxy is hidden from the prying eyes of optical telescopes by clouds of obscuring dust and gas. ... Near the outskirts of the Small Magellanic Cloud, a satellite galaxy some 200 thousand light-years distant, lies 5 million year young star cluster NGC 602. ...