|Exoplanet||List of exoplanets|
|Discovery method||Direct imaging|
|Discovery site||Pan-STARRS PS1 telescope, Haleakalā|
PSO J318.5-22 is a rogue planet, an extrasolar object of planetary mass that does not appear to have a host star. It is approximately 80 light-years away, and belongs to the Beta Pictoris moving group. The object was discovered in 2013 in images taken by the Pan-STARRS PS1 wide-field telescope. PSO J318.5-22's age is inferred to be 12 million years, the same age as the Beta Pictoris group.
The team leader, Michael Liu 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 systems soon after they formed through planetary accretion, or they may have been formed by some other means. Estimated temperatures inside its clouds exceed 800 °C. The clouds, made of hot dust and molten iron, show how ubiquitous clouds are in planets and planet-like objects. 
- Michael C. Liu; Eugene A. Magnier; Niall R. Deacon; Katelyn N. Allers; et al. (2013-10-01). "The Extremely Red, Young L Dwarf PSO J318-22: A Free-Floating Planetary-Mass Analog to Directly Imaged Young Gas-Giant Planets". Astrophysical Journal Letters. 777. arXiv:. Bibcode:2013ApJ...777L..20L. doi:10.1088/2041-8205/777/2/L20.
- Gemini Observatory (2013-10-07). "Gemini Confirms Lonely Planet Floating in Space".
- Star-Advertiser Staff (2013-10-09). "Astronomers using Hawaii telescopes discover planet without a star". Honolulu Star-Advertiser. Honolulu Star-Advertiser.
- "A Strange Lonely Planet Found Without a Star". Science Daily. October 9, 2013.
- Institute for Astronomy (2013-10-09). "A Strange Lonely Planet Found without a Star". University of Hawaii.
- Young planet, six times more massive than Jupiter, found hanging alone without star Shelly Jones, Pentagon Post, 12th October 2013
- Alan Boyle (9 October 2013), Astronomers say they've spotted lonesome planet without a sun, NBC News
- http://www.bbc.com/news/uk-scotland-edinburgh-east-fife-34712877 Edinburgh University astronomers find sunless world