Scientists have discovered a new class of alien planets that appear to be floating through space with no attachment to a host star. New research identifying ten of these "orphan" planets suggests there may be more of them, just in our Milky Way galaxy alone, than there are stars.
Astronomers from Japan and New Zealand calculate that these Jupiter-sized rogues likely outnumber normal planets that orbit stars by more than 50 percent, and might be twice as common as stars like our Sun. They believe the lone worlds were probably ejected from developing planetary systems or knocked out of orbit by some catastrophic event.
There is a remote chance that some of these seemingly free-floating planets could actually be in an extremely distant orbit around a star.
The research team, led by Takahiro Sumi from Osaka University in Japan, studied data from a two-year scan of 50 million stars at the center of our Milky Way galaxy. Using a method called gravitational microlensing, they could see when a massive object passed in front of an observed star and bent or magnified its light. Sumi's team spotted ten such objects that did not appear to be orbiting any nearby host star, and concluded that they were rogue planets roughly the size of Jupiter, drifting in interstellar space between 10,000 and 20,000 light years from Earth.
Other astronomers say the discovery of a new class of planet-sized objects has profound implications for our understanding of the cosmos and will inspire much follow-up research.
The orphan planet study is published in the journal Nature.
Some information for this report was provided by AP, AFP and Reuters.