Fluffy, with a core of density. That’s what the interior of the asteroid 87 Sylvia likely looks like, astronomers say. The neatest thing about that observation? It didn’t require a drill or even a spacecraft visit. That came from watching the orbits of the asteroid’s two moons, Romulus and Remus. The discovery illustrates the power … Continue reading Tale Of Two Moons Reveals Asteroid’s Insides