Nasa's 'holy grail': Newly-discovered solar system may harbour secrets of alien life
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Life may have evolved on at least three planets within a newly discovered solar system that is 39 light years from Earth, it was announced last night.
Astronomers at the National Aeronautics and Space Administration (Nasa) have detected no fewer than seven roughly Earth-sized worlds orbiting a dwarf star in the system, it was announced last night.
Scientists had previously only identified a tiny number of so-called "exoplanets", believed to have the qualities needed to support life.
However, the new system contains an unprecedented number of Earth-sized, probably rocky, planets and is being hailed as an "accelerated leap forward" in the search for extraterrestrial life. Three of the new planets are said to be particularly promising because they could sustain oceans.
Thomas Zurbuchen, associate administrator of Nasa's Science Mission Directorate, told a press conference in Washington: "This gives us a hint that finding a second Earth is not a matter of 'if', but 'when'."
The planets were detected using Nasa's Spitzer Space Telescope and several ground-based observatories.
"The planets are all close to each other and very close to the star, which is very reminiscent of the moons around Jupiter," lead researcher Michael Gillon, of the University of Liege, said.
"Still, the star is so small and cold that the seven planets are temperate, which means that they could have some liquid water - and maybe life, by extension - on the surface."
The team determined that all the planets in the system are similar in size to Earth and Venus, or slightly smaller. Density measurements suggest at least the innermost six planets are rocky. Because the star is so dim, the planets are warmed gently despite having orbits much smaller than that of Mercury, the planet closest to our Sun.
Key observations were made by the Trappist robotic telescope at La Silla, Chile, which gives the system its name.
Three planets - Trappist-1 e, f and g - orbit in the "habitable" or "Goldilocks" zone where temperatures are suited to surface oceans.
Nasa's Hubble Space Telescope is already being used to search for atmospheres around the planets. Future telescopes, including the proposed European Extremely Large Telescope and the James Webb Space Telescope, may be powerful enough to detect markers of life, such as oxygen, in the atmospheres of exoplanets.
"We have made a giant accelerated leap forward in the search for habitable worlds and life in other worlds.", Prof Sara Seager, an expert in planetary science and physics at the Massachusetts Institute of Technology, said.
Will Scientists discover alien lifeforms in our lifetime