Our Milky Way is just one of many billions of galaxies that dot the cosmos—an ordinary spiral in a universe filled with them. The unspecialness of our corner of space, an idea known as the Copernican principle, is a cornerstone of modern cosmology. But it doesn't mean that the Milky Way has to be totally average in every respect. Among the more than 20 satellite galaxies that hover around the Milky Way in a kind of galactic entourage are two large satellites known as the Large and Small Magellanic Clouds. Stargazers and navigators have known about them since before the age the telescope. Yet today's astrophysicists have had a hard time explaining how they got there. Computer simulations of galaxy formation and evolution tend not to produce bright satellite galaxies akin to the two Magellanic Clouds. So researchers had to ask: Are the simulations flawed—perhaps in the way that they account for the all-important role of the mysterious dark matter—or is the Milky Way just a bit of an oddball? With help from new supercomputer simulations and from a universe-mapping telescope project called the Sloan Digital Sky Survey, the matter now seems to have been settled. Sloan survey says? Oddball. In a state-of-the-art affirmation of the earlier models, the latest round of supercomputer simulations again showed that a Milky Way–size galaxy should rarely gather satellites the size of the Magellanic Clouds. And telescopic observations of thousands of real-life galaxies and their satellites have confirmed that theoretical prediction. Full article here.