Look up in the sky tonight towards the southeast in the constellation Cetus. There’s a naked-eye star named Tau Ceti that lies about 12 light-years away from Earth, and astronomers have discovered a system of at least five planets orbiting Tau Ceti, including one in the star’s habitable zone. While the recent discovery of a Earth-sized planet around the triple star system Alpha Centauri is the closest planet that has been discovered at just 4.3 light years away, this new discovery is the closest single sun-like star that we know of to host of an entire system of planets. The five planets are estimated to have masses between two and six times the mass of the Earth, making it the lowest-mass planetary system yet detected. The planet in the habitable zone of the star has a mass around five times that of Earth, making it the smallest planet found to be orbiting in the habitable zone of any Sun-like star. “This discovery is in keeping with our emerging view that virtually every star has planets, and that the galaxy must have many such potentially habitable Earth-sized planets,” said astronomer Steve Vogt from UC Santa Cruz, coauthor of the paper describing the discovery. “We are now beginning to understand that nature seems to overwhelmingly prefer systems that have multiple planets with orbits of less than 100 days. This is quite unlike our own solar system, where there is nothing with an orbit inside that of Mercury. So our solar system is, in some sense, a bit of a freak and not the most typical kind of system that Nature cooks up.”
Posted on: Mon, 04 Nov 2013 20:03:01 +0000