A whole new world

Astronomers have found that the chemical composition of superficially "Earth-like" planets outside our solar system may be very different in bulk composition to the Earth. The team based at the Instituto de Astrofísica de Canarias, in the Canary Islands, suggests that the discovery may have dramatic consequences for finding extraterrestrial worlds that have environments akin to those on Earth that might theoretically support life. Theoretical studies show that the ratios of C:O and Mg:Si are the most critical elemental ratios in the determination of an Earth-like planet's mineralogy. The new work shows that the elemental abundances in proto-planet forming stars can vary wildly from that seen in the Earth.