A planet without a sun has been discovered by astronomers. 

Astronomers discovered a large planet floating freely through space with no star to orbit. Most planets orbit a host star, like the Earth revolves around the sun, The cold planet is a difficult one to find because it isn't orbiting a star, but that also makes it easier to study.The extrasolar planet, named PSO J318.5-22, appears to be drifting through space.

The new planet was found by a team of astronomers who were working at the University of Hawaii at Mamoa. It is about 80 light years away from earth. Astronomers compared the newly discovered planet to a young Jupiter.

In a statement, astronomy team leader Michael Liu said "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. I had often wondered if such solitary objects exist, and now we know they do."

Dr Michael Liu of the Institute for Astronomy identified the rogue planet from its "faint and unique heat signature."

PSO J318.5-22 has the same properties of other gas-giant planets that orbit around young stars.

The planet without a sun is a free-floating planet. It was given the name "PSO J318.5-22." The new planet is estimated to be about 12 million years old, which is young for a planet. For example, it is believed that the Earth is about 4.5 billion years old.

British newspaper The Independent explained that scientists using techniques that involve "detecting the decreased transmission of light as a planet passes in front of its sun have found hundreds of "exoplanets" since the mid-1990s. But astronomers found PSO J318.5-22 while failed stars, called brown dwarfs, which are faint and red in color, using the Pan-STARRS 1 telescope.

One of the authors of the study, Niall Deacon, put out a news release saying "planets found by direct imaging are incredibly hard to study, since they are right next to their much brighter host stars."

Experts say it will be easier to study PSO J318.5-22 because it isn't orbiting a star.