2:25 PM | *NASA discovers first known system of seven Earth-size planets around a single star*

This artist's concept shows what each of the TRAPPIST-1 planets may look like, based on available data about their sizes, masses and orbital distances (not drawn to scale).
Credits: NASA/JPL-Caltech
 

Overview
NASA’s Spitzer Space Telescope has revealed the first known system of seven Earth-size planets around a single star and three of these are believed to be in the habitable zone – the area around the parent star where a rocky planet is most likely to have liquid water.  The discovery sets a record for the greatest number of habitable-zone planets found around a single star outside of our solar system.  All of these seven planets could have liquid water, the chances are highest with the three in the habitable zone.
 
Discussion
This system of planets is relatively close to us – about 40 light years (235 trillion miles) – and is located in the constellation Aquarius.  Because these planets are located outside of our solar system, they are known officially as exoplanets.  This exoplanet system is called TRAPPIST-1, named for the Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile. These findings were unveiled today at a NASA news briefing in Washington, D.C. and published in the journal Nature.  

Using Spitzer data, scientists 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.  Following up on the Spitzer discovery, NASA's Hubble Space Telescope has initiated the screening of four of the planets, including the three inside the habitable zone. 

Meteorologist Paul Dorian
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