Giant Asteroid Could Have Had Molten Core

21 Lutetia, hiding out between Mars and Jupiter, has a core that astronomers believe could be the sign of a planet that never made it.

One of the largest asteroids ever found could have been a planet that never quite made it to fruition, according to three new studies of 21 Lutetia. The asteroid, in the belt between Mars and Jupiter, was observed up close by the European Space Agency's Rosetta probe last year. Measuring 132 x 100 x 76 kilometres, 21 Lutetia is one of the biggest non-planetary bodies in the solar system, and now data from the Rosetta probe indicates that it could very well have had a molten core millions of years ago – a sign that it might have been on course to become a planet when the solar system first came into being. The Rosetta team concludes that it could have been a fetal planet because its density is much higher than those of other asteroids, due to what they believe is now a metal-rich core. If it is indeed hiding such a core beneath its battered and beaten surface, then Lutetia would be the first ever asteroid to be confirmed to boast such planetary features.