Earth-like Exoplanets: The stunning discovery of seven Earth-like planets orbiting a small star in our galaxy opens up the most promising hunting ground so far for life beyond the Solar System, researchers said Wednesday. All seven roughly match the size and mass of our own planet and are almost certainly rocky, and three are perfectly perched to harbour life-nurturing oceans of water, they reported in the journal Nature. Most critically, their proximity to Earth and the dimness of their red dwarf star, called Trappist-1, will allow astronomers to parse each one’s atmosphere in search of chemical signatures of biological activity. The Trappist-1 system, a mere 39 light years distant, has the largest number of Earth-sized planets known to orbit a single star.
It also has the most within the so-called “temperate zone” — not so hot that water evaporates, nor so cold that it freezes rock-solid. The discovery adds to growing evidence that our home galaxy, the Milky Way, may be populated with tens of billions of worlds not unlike our own — far more than previously suspected. “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 NASA’s Science Mission Directorate. “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.” The planets are so close to each other and the star that there are seven of them within a space five times smaller than the distance from Mercury to our sun. This proximity allows the researchers to study the planets in depth as well, gaining insight about planetary systems other than our own. Over the next decade, the researchers want to define the atmosphere of each planet, as well as to determine whether they truly do have liquid water on the surface and search for signs of life.