Scientists have discovered a young exotic planet that is six times more massive than Jupiter, but this young planet has been discovered floating all alone without a sun about 80 light-years from Earth.

The planet, dubbed PSO J318.5-22, formed a mere 12 million years ago – a newborn in planet lifetimes. PSO J318.5-22 was discovered during a search for the failed stars known as brown dwarfs. Due to their relatively cool temperatures, brown dwarfs are very faint and have very red colours.

An international team of astronomers identified this lonely planet from its faint and unique heat signature by the Pan-STARRS 1 (PS1) wide-field survey telescope on Haleakala, Maui.

Follow-up observations using other telescopes in Hawaii show that it has properties similar to those of gas-giant planets found orbiting around young stars. And yet PSO J318.5-22 is all by itself, without a host star.

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The discovered planet PSO J318.5-22 stood out as an oddball, redder than even the reddest known brown dwarfs. The planet is extremely cold and faint, about 100 billion times fainter in optical light than the planet Venus. Most of its energy is emitted at infrared wavelengths.

“We have never before seen an object free-floating in space that looks like this. It has all the characteristics of young planets found around other stars, but it is drifting out there all alone,” said team leader Dr Michael Liu of the Institute for Astronomy at the University of Hawaii at Manoa.

“I had often wondered if such solitary objects exist, and now we know they do,” said Liu.

According to the researchers, PSO J318.5-22 is one of the lowest-mass free-floating objects known, perhaps the very lowest.

The scientists say, the planet’s most unique aspect is its similar mass, colour, and energy output to directly imaged planets.
“Planets found by direct imaging are incredibly hard to study, since they are right next to their much brighter host stars. PSO J318.5-22 is not orbiting a star so it will be much easier for us to study. It is going to provide a wonderful view into the inner workings of gas-giant planets like Jupiter shortly after their birth,” said Dr Niall Deacon of the Max Planck Institute for Astronomy in Germany and a co-author of the study.