In what can be easily described as one of the most unique discoveries made during the century, a team of astronomers have come across a free-floating planet that’s estimated to possess a mass six times that of Jupiter. Named PSO J318.5-22, the relatively young planet is said to be 12 million years old and 80 light years away from Earth.

Floating in space without a star, PSO J318.5-22 has left astronomers puzzled about how it happened to find a place in space. While one school of thought feels that it came to be formed from a cluster of hydrogen gas, there are others who opine that the planet began its life near a star, and later became disassociated out of its orbit.

Noting that the newly-found planet was floating in space like the sun, Dr. Eugene Magnier, University of Hawaii, Manoa, says PSO J318.5-22 can also be regarded as a brown dwarf. Comparing the extremely small size of the planet with that of brown dwarfs, he however hastened to add that there was no clear idea about the planet. “We still don’t have a good idea about where to draw the line between a planet and brown dwarf”, Dr. Magnier, who heads the data processing team for Pan-STARRS 1 (PS1), said.

Never Been Seen Before

According to Dr. Michael Liu of the Institute for Astronomy at the University of Hawaii, such an object has never been sighted before. “We have never before seen an object free-floating in space that looks like this”. Stating that PSO J318.5-22 had all the features of young planets noticed in the vicinity of other stars, Dr. Liu, who traced the rogue planet from its ‘faint and unique heat signature’, said the new planet was found drifting out all by itself. “I had often wondered if such solitary objects exist, and now know they do,” he added.

While planets outside the solar system have been identified on several occasions in the recent past, only a very few of them found around young stars have been imaged directly. PSO J318.5-22, which is the lowest-mass free-floating object to be sighted, is found to share a lot of similarity with these planets in terms of mass, color and energy output.

Impressive Find

Dr. Niall Deacon of the Max Planck Institute for Astronomy in Germany, said planets spotted through direct imaging were quite hard to study as they are located very close to their much brighter host stars. However, by virtue of not orbiting a star PSO J318.5-22 will prove much easier to study, Dr. Liu, who made use of the PS1 wide-field survey telescope on Haleakala Maui for discovering the planet, said.

The international team of astronomers, who discovered PSO J318.5-22, said they succeeded in directly measuring the distance of the planet from Earth by keeping a strict vigil on the position of the planet for a couple of years with the help of the Canada-France-Hawaii Telescope. It’s after taking into account the distance thus obtained and the planet’s motion that the astronomers decided to classify PSO J318.5-22 along with other young stars known as the Beta Pictoris group that came into existence some 12 million years ago.