Earth-Sized Worlds

About 40 light years (235 trillion miles from Earth), seven Earth-size planets orbit around a single star. Called the TRAPPIST-1 system, all seven planets could have liquid water – key to life as we know it – under the right atmospheric conditions. But the chances are highest with the three planets that were found in the habitable zone, the area around the parent star where a rocky planet is most likely to have liquid water. The initial discovery of the system was made by researchers using The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile, who discovered two planets in the system by observing the dip in light that occurs when a planet passes between its sun and Earth. Assisted by several ground-based telescopes, NASA'a Spitzer Space Telescope, which trails Earth's orbit around the sun, confirmed their existence and discovered five additional planets. Researchers plan to study the atmospheres of these planets to determine their similarities – or differences – from Earth. Watch the video to learn more.

See NASA.gov