A HAMBURGER-shaped asteroid is challenging our understanding of asteroid formation. Images from the Hubble Space Telescope have revealed that Ceres, the largest body in the asteroid belt between Mars and Jupiter, is not a perfect sphere as previously thought, but is squashed at both ends.
Till now astronomers reckoned that the asteroid, which has a diameter of 950 kilometres, had just enough mass to pull itself into a sphere, but not enough to create other planet-like features. But when Lucy-Ann McFadden at the University of Maryland, College Park, and her colleagues examined Hubble鈥檚 images of Ceres they realised this was wrong. 鈥淚t has been squashed down at the ends under its own gravity, just like Earth,鈥� she says.
The team has calculated that Ceres鈥檚 gravity must also have pulled heavy materials into a rocky core and left an icy mantle, another planet-like feature (Nature, vol 437, p 224).
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