IT caused a sensation when the discovery was first announced a year ago. Seven roughly Earth-sized worlds were found in orbit around just one star — TRAPPIST 1.
And that dim red dwarf star is relatively close in astronomical terms: just 39 light years away.
This means it and its clutch of rocky worlds are potentially within the reach of current technology to observe their composition.
Four of the planets sit neatly within the star’s ‘Goldilocks zone’, a distance where it was neither too hot nor too cold to sustain liquid water.
Now the Hubble Space Telescope and European Southern Observatory have revealed that at least five of the planets consist of up to 5 per cent water. In comparison, Earth’s oceans account for just 0.02 per cent of our planet’s mass.
The potential the existence of so many water worlds in one place has for the emergence of life has left astronomers sitting on the edge of their seats.
Astronomers used the Hubble Space Telescope to learn more about the Trappist system by studying the planets’ atmospheres as they passed in front of their star, appearing as a dark, travelling dot from the observer’s point of view.
The findings were published overnight in two papers in the journals Nature Astronomy, and Astronomy and Astrophysics.