Astronomers using the European Southern Observatory’s New Technology Telescope discovered that asteroids have a highly varied internal structure. The subject--asteroid Itokawa. This asteroid was the target of the Japanese spacecraft Hayabusa in 2005, which took samples of an asteroid for the first time and sent them back to Earth. New observations of Itokawa reveal that different parts of the asteroid have different densities, which they determined caused a slow increase in acceleration. This is the first time scientists have ever determined what it’s like inside of an asteroid and they say this knowledge is a significant step toward understanding rocky bodies in our Solar System.