Seven worlds orbit the ultracool dwarf star TRAPPIST-1. A mere 40 light-years away, many of the exoplanets were discovered in 2016 using the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) located in the Atlas Mountains of Morocco , and later confirmed with telescope including NASA's Spitzer Space Telescope . The TRAPPIST-1 planets are likely all rocky and similar in size to Earth, and so compose one of the largest treasure troves of terrestrial planets ever detected around a single star. Because they orbit very close to their faint, tiny star they could also have regions where surface temperatures allow for the presence of ice or even liquid water, a key ingredient for life . Their tantalizing proximity to Earth makes them prime candidates for future telescopic explorations of the atmospheres of potentially habitable planets . All seven exoplanets appear in the featured illustration, which imagines a view from the most distant known world of this system, ...