PSO J318.5-22 is a confirmed, extrasolar planet which does not appear to be orbiting any type of star. It is approximately 80 light-years away from Earth, in the constellation of Pictor. The estimated age of this planet is around 12 million years.
Dr Michael Liu, the team leader of the Institute for Astronomy at the University of Hawaii, stated: "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." Current theories about such objects include the possibility that gravitational perturbations may have kicked them out of their planetary cradles soon after they were formed through planetary accretion, or they may have formed in another way. PSO J318.5-22 is also speculated to be a failed star.
- Discovery date: 2013
- Discovery method: Direct imaging
- Discovery site: Pan-STARRS PS1 telescope, Haleakalā, Maui, Hawaii
- Discovery status: Published