The search for extra-terrestrial life may have taken a leap forward this week, with news that a Jet Propulsion Laboratory-managed space telescope has confirmed the discovery of seven Earth-like planets, three of which are considered to be in the “habitable zone,” orbiting around a single star.
NASA officials said the discovery sets a record for the largest number of habitable-zone planets around a single star outside our solar system. The three planets in the habitable zone are considered most likely to have water—the key building block of life —but all seven could potentially have it.”
“This is the most exciting result I have seen in the 14 years of Spitzer operation,” said Sean Carey, manager of NASA’s Spitzer Science Center at Caltech. “Spitzer will follow up in the fall to further refine our understanding of these planets so that the James Webb Space Telescope can follow up. More observations of the system are sure to reveal more secrets.”
The planets are located about 40 light-years from Earth, or about 235 trillion miles away, in the constellation Aquarius.
The system has been dubbed TRAPPIST-1 after the Transiting Planets and Planetesimals Small Telescope in Chile, which was the first to discover three planets in the system. Spitzer later confirmed the existence of two of those three, and discovered five more, bringing the discovery to a total of seven planets.
All of the planets—which are officially dubbed exoplanets because they are outside our solar system—are likely to be rocky, and all seven are orbiting closer to their star than Mercury is to our own sun. They are also believed to be “tidally locked” to the star, meaning they do not rotate as they orbit, so one side of each planet is perpetual daytime and the other is perpetually night. The weather systems of the planets, therefore, are likely dramatically different than Earth.
“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 toward that goal.”
The Spitzer telescope spent 500 continuous hours last fall studying the planets, and NASA’s Hubble Space Telescope has been following up, working to determine the types of atmospheres the planets have. Last year, Hubble researchers determined that the two inner-most planets do not have the puffy, hydrogen-dominated atmospheres typical of gaseous planets such as Neptune, giving support to the theory that the planets are rocky worlds.
NASA’s Kepler space telescope is also examining the planets, and NASA plans to use its new James Webb Space Telescope, set for launch in 2018, to do further analysis. The Webb telescope has more detailed instruments that can detect “chemical fingerprints” of substances such as water, methane, oxygen or ozone. It can also determine temperatures and surface pressures, which are key factors in determining, if the planets are truly habitable.