Three planets with sizes and temperatures akin to those of the Earth and Venus are circling a dwarf star 40 light-years away. The star in question, named TRAPPIST-1 after the telescope used to observe it, is weaker and cooler than the Sun at the heart of our solar system. "With such short orbital periods, the planets are between 20 and 100 times closer to their star than the Earth to the Sun. The structure of this planetary system is much more similar in scale to the system of Jupiter's moons than to that of the solar system," said lead astronomer Michaël Gillon of the University of Liège in Belgium.
