NASA has announced that the Spitzer Space Telescope had identified a dwarf star about 40 light years away, with seven Earth-size planets revolving around it. Three of those planets are in the habitable zone, meaning they have temperatures that could support liquid water and possibly sustain life. The star itself has been named TRAPPIST-1, and the planets are named the same, with letters appended to denote their position.
Using Spitzer data, the team precisely measured the sizes of the seven planets and developed first estimates of the masses of six of them, allowing their density to be estimated.
Based on their densities, all of the TRAPPIST-1 planets are likely to be rocky. Further observations will not only help determine whether they are rich in water, but also possibly reveal whether any could have liquid water on their surfaces. The mass of the seventh and farthest exoplanet has not yet been estimated – scientists believe it could be an icy, "snowball-like" world, but further observations are needed.
"The seven wonders of TRAPPIST-1 are the first Earth-size planets that have been found orbiting this kind of star," said Michael Gillon, lead author of the paper and the principal investigator of the TRAPPIST exoplanet survey at the University of Liege, Belgium. "It is also the best target yet for studying the atmospheres of potentially habitable, Earth-size worlds."
The planets revolve closer to their star than Earth to the sun, because TRAPPIST-1 is smaller and cooler than our sun. The planets are also fairly close to one another. Read more about the discovery at NASA, and at the website dedicated to TRAPPIST-1. -via The Daily Dot