NASA discovers solar system of 7 Earth-sized planets
Some of the worlds could contain water, and a chance of alien life
TOMOYUKI KAWAI, Nikkei staff writer
WASHINGTON -- NASA has reported the discovery of seven Earth-sized worlds revolving around a dwarf star 39 light years away, some of which may contain water and possibly life outside this solar system.
The findings, from the U.S. space agency's joint research project with the University of Liege in Belgium, was published online by the British science magazine Nature on Wednesday.
The planets form a system surrounding Trappist-1, a star in the Aquarius constellation. They range from 0.76 to 1.13 times the size of Earth. Finding a solar system with seven planets is rare in itself, and six of them have masses similar to that of Earth and are likely to be composed of rock. NASA's Spitzer Space Telescope and other instruments were used to discover the planets.
At least three of the planets may contain liquid water. They are situated in a habitable zone, a distance from their star that is neither hot enough to evaporate all water nor cold enough to freeze it.
Trappist-1 is a young star that will last another 10 trillion years. That is enough time for time to life to evolve, it is thought.
In July 2015, NASA discovered Kepler-452b, another "Earth cousin" located 1,400 light years away that may contain water.