PARIS – Tau Ceti, one the stars closest to us, is a good candidate for hosting an Earth-like planet, astronomers say.
Located a relatively close 12 light-years away, the star, which resembles our sun, has five planets that orbit it in a balmy zone that would allow for surface water, giving it the best chance for nurturing life, they said.
One of the planets has a mass about five times that of the Earth, making it the smallest planet found so far in this vital zone.
Around 800 exoplanets — worlds orbiting stars other than our own — have been spotted since 1995. But none is a home away from home. These planets are either uninhabitable gas giants or big rocky worlds that swing so close to their star they are roasted.
The quest is to find a rocky planet that is not only close to the mass of Earth but is also located in the so-called Goldilocks zone, an orbital distance from the star where temperature is neither too hot nor too cold, but just right to sustain liquid water, an essential condition for life as we know it.
The Tau Ceti finding was made by astronomers from Australia, Britain, Chile and the United States who applied a new technique to filter data from more than 6,000 observations. By doing so, they believe they rooted out distorting signals, called “noise,” that masked the existence of low-mass planets.
They applied the technique to light from Tau Ceti, and determined it is not a lone star but in fact one with a planetary system.
“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,” Steve Vogt, a veteran hunter of exoplanets, said in a press release issued by Britain’s University of Hertfordshire.
“We are now beginning to understand that nature seems to overwhelmingly prefer systems that have multiple planets with orbits of less than one hundred days,” he said.
“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.”
On Oct. 17, European astronomers reported they had detected a planet with roughly the mass of Earth orbiting Alpha Centauri B, which is only 4.3 light-years away. However, the planet itself is not “another Earth,” as it is not in the Goldilocks zone. It zips around the star at a scorchingly close distance, and liquid water could not exist on it.