7 EXOPLANET NEWS by Camille M. Carlisle Earth-Size Planets Orbit Dim Star Several of TRAPPIST-1's worlds might have the potential for liquid surface water - or have had their atmospheres torn off. ESO / M. KOR NMESSER q ALIEN SKY Artist's concept of what the sky might look like from above one of the seven known terrestrial planets in the TRAPPIST-1 system. T he star TRAPPIST-1 is an unassuming, M8 red dwarf star. It lies 39 light-years away in the constellation Aquarius, shining at a measly apparent magnitude of 19. Closer in size to Jupiter than to the Sun, the dwarf puts out less than a thousandth as much light as our star. Last year, Michaël Gillon (University of Liège, Belgium) and colleagues announced that a trio of small exoplanets orbits this pipsqueak star (S&T: Aug. 2016, p. 12). The team detected the exoplanets using the transit technique, which catches the tiny dip in starlight when a planet passes in front of its host star from our perspective. Now, after an intensive 12 J U N E 2 0 1 7 * SK Y & TELESCOPE