Searching for nearby exo-Earths around cool stars with ExTrA

Sited at ESO’s La Silla Observatory in northern Chile, the French national ExTrA (Exoplanets in Transits and their Atmospheres) project is amongst a new generation of planet-hunting telescopes. Comprising three 60-centimetre telescopes, the facility utilises the transit method to detect Earth-sized worlds in the Milky Way — looking for slight dips in the light from a star that could be caused by a planet passing across the star’s disc and obscuring some of its light.