By Tanya Lewis
Not all planets are content to dutifully circle a star. A new rogue planet has been spied roaming free among a pack of young stars about 115 to 160 light-years from Earth.
It’s not a planet in the conventional sense, because it doesn’t orbit a star. Yet it’s between four and seven times the mass of Jupiter, well within planetary size range. The object appears to be a young, cold planet in a cluster of about 30 stars moving together called AB Doradus, astronomers report in the December Astronomy & Astrophysics. The free-floating planet is the closest to Earth yet discovered, scientists say.
“It’s quite a nice discovery — probably the clearest example of a planetary mass object that’s very young like this,” says astrophysicist Philip Lucas of the University of Hertfordshire in England, who was not involved with the study.