... One of the brightest galaxies in planet Earth's sky and similar in size to the Milky Way, big, beautiful spiral M81 lies 11.8 million light-years away in the northern constellation Ursa Major. ... But astronomers are now reporting the discovery of a remarkable system of three planets orbiting Gliese 581, including the most earth-like planet found beyond our solar system. ... NGC 3372, known as the Great Nebula in Carina, is home to massive stars and changing nebula. The Sun in Three Dimensions . ...