NASA’s Spitzer Space Telescope has revelaed the first known system of seven Earth-size planets around a single star. Three of these planets are firmly located 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 new record for greatest number of habitable-zone planets found around a single star outside our solar system. All of these 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 in the habitable zone.

The briefing participants were:

· Thomas Zurbuchen, associate administrator of the Science Mission Directorate at NASA Headquarters in Washington

· Michael Gillon, astronomer at the University of Liege in Belgium

· Sean Carey, manager of NASA’s Spitzer Science Center at Caltech/IPAC, Pasadena, California

· Nikole Lewis, astronomer at the Space Telescope Science Institute in Baltimore

· Sara Seager, professor of planetary science and physics at Massachusetts Institute of Technology, Cambridge