Astronomers have detected three exoplanets just 40 light years from Earth whose sizes and temperatures are comparable to those of Earth. The planets may be the best targets found so far for the search for life outside the solar system.Because the system is relatively close to Earth, co-author Julien de Wit, a postdoc at MIT, says scientists will soon be able to study the planets’ atmospheric compositions, as well as assess their habitability and whether life actually exists within this planetary system.