Astronomers have found at least seven Earth-sized planets orbiting the same star, called TRAPPIST-1, 40 light-years away. The findings were announced today at a news conference at NASA Headquarters in Washington.
Three of the planets are in the habitable zone, where liquid water can exist on the surface of rocky planets, as it’s not too hot or cold.
The discovery sets a new record for greatest number of habitable-zone planets found around a single star outside our solar system.
“The discovery gives us a hint that finding a second Earth is not just a matter of if, but when,” Thomas Zurbuchen, associate administrator of the Science Mission Directorate at NASA Headquarters, said at a news conference announcing the discovery.
“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,” said Zurbuchen.
At 235 trillion miles from Earth, the system of planets is relatively close to us, in the constellation Aquarius.
The exoplanet system is called TRAPPIST-1, named for The Transiting Planets and Planetesimals Small Telescope (TRAPPIST) in Chile. In May 2016, researchers using TRAPPIST announced they had discovered three planets in the system.
Assisted by several other ground-based telescopes, including the European Southern Observatory’s Very Large Telescope, NASA’s Spitzer Space Telescope confirmed the existence of two of these planets and discovered five additional ones, increasing the number of known planets in the system to seven.
“This is the most exciting result I have seen in the 14 years of Spitzer operations,” said Sean Carey, manager of NASA’s Spitzer Science Center at Caltech/IPAC in Pasadena, California. “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.”
NASA’s upcoming James Webb Space Telescope, launching in 2018, will help astronomers plan for follow-up studies. 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.