Newfound Alien Planet is a Metal-Heavy Cannonball

A Mercury-like planet the size of Earth orbits 100 times closer to its star, K2-229, than Earth does the sun. Credit: L. Calçada/ESO
Scientists have discovered a metal-heavy cannonball of an exoplanet resembling an Earth-size version of Mercury.

By Charles Q. Choi |

This newfound world could help shed light on the mysteries of Mercury’s origins and evolution.

Previous research suggested that Earth, Venus and Mars have metal cores that make up only about one-third of the mass of their planets. In contrast, Mercury is mostly metal, with a metallic core that makes up about two-thirds of the planet’s mass. [Inside Planet Mercury (Infographic)]

It remains hotly debated why Mercury differs so much from its rocky siblings. Now, researchers have discovered an alien version of Mercury that could better explain the history of the solar system’s innermost world.

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