Signs of water on Belgian-discovered exoplanets

Seven exo-planets in a distant solar system discovered by scientists in Liège could potentially hold more water than Earth, according to a new study.

An international team led by Liège astronomer Michaël Gillon has been busy finding out more about the planets they discovered last year that orbit a dim star nicknamed TRAPPIST-1, about 40 light years away.

New research into the planets' densities, published on Monday in the journals Nature Astronomy and Astronomy and Astrophysics, suggest some of the planets could contain up to five percent of their mass in water.

According to the study, the fourth planet in the system, TRAPPIST-1e, bears the closest resemblance to Earth in terms of size, density and radiation from the star - an "ultracool dwarf star", which is far smaller and cooler than the Sun.

Gillon said: "This result highlights the huge interest of exploring nearby ultracool dwarf stars like TRAPPIST-1 for transiting terrestrial planets."