JACKSONVILLE, Fla. – NASA announced in a press conference today that their Spitzer space telescope revealed a new system consisting of seven new planets, relatively the same size as Earth, orbiting around a dwarf star. A number of the seven planets appear to be in the habitable zone, meaning liquid water is most likely present and could possibly support life. The planets are exoplanets, meaning they do not rotate around our star, the sun. You can watch the announcement here...
This discovery is unprecedented in terms of greatest number of planets within the habitable zone discovered around a single star outside of our solar system. All seven of the newly discovered planets could have liquid water under the correct atmospheric conditions, but specifically three of the planets have the best chances to have liquid water flowing on the surface. Currently, the Hubble space telescope is scanning the atmospheres of these planets to help determine if liquid water is present.
The newly discovered system is relatively close in galactic terms- only about 40 light years away from us in the constellation Aquarius. The (relatively) small dwarf star at the center of these seven planets is named TRAPPIST-1 and is slightly larger than Jupiter and 2,000 times dimmer than our sun. Because it is so much more dim, scientists estimate than even the planets orbiting closest to TRAPPIST-1 may still have liquid water. Dwarf stars like TRAPPIST-1 are common in our Milky Way galaxy.
"This discovery could be a significant piece in the puzzle of finding habitable environments, places that are conducive to life,” said Thomas Zurbuchen, associate administrator of the agency’s Science Mission Directorate in Washington. “Answering the question ‘are we alone’ is a top science priority and finding so many planets like these for the first time in the habitable zone is a remarkable step forward toward that goal.”
Based on the measured density, the new planets are expected to be mostly rocky. The outermost planet orbiting TRAPPIST-1 is believed to only be possible for an icy, snowball-like presence of water because of its distance from the star.
"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."
NASA reports tha all seven of the TRAPPIST-1 planetary orbits are closer to their host star than Mercury is to our sun. The planets also are very close to each other. If a person was standing on one of the planet’s surface, they could gaze up and potentially see geological features or clouds of neighboring worlds, which would sometimes appear larger than the moon in Earth's sky.
The planets may also be tidally locked to their star, which means the same side of the planet is always facing the star, instead of turning as it orbits like Earth, therefore each side is either perpetual day or night. This could mean they have weather patterns totally unlike those on Earth, such as strong winds blowing from the day side to the night side, and extreme temperature changes.
The Spitzer, Hubble, and Kepler telescopes will help astronomers plan for follow-up studies using NASA's upcoming James Webb Space Telescope, launching in 2018. With much greater sensitivity, Webb will be able to detect the chemical fingerprints of water, methane, oxygen, ozone, and other components of a planet's atmosphere. Webb also will analyze planets' temperatures and surface pressures – key factors in assessing their habitability.