THE LONE PLANET
PSO J318.5-22
Confirmed by images taken with the Pan-STARRS 1 (PS1) widefield telescope, PSO J318.5-22 is an exoplanet that prefers the single life. In short, it doesn’t seem to be orbiting a star at all.
Experts have affectionately dubbed this gaseous world as a rogue planet. But, at approximately 80 light years away, this oddball isn’t entirely a loner as it sits among the Beta Pictoris Moving Group – a gaggle of youthful stars. However, the fact that PSO J318.5-22 isn’t dancing around any members in the group – which have been dated somewhere around 12 million years old – has thrown astronomers a bit of a curveball.
At 6.5 Jupiter masses, this world is too light to be a brown dwarf – the dividing line that separates planets and stars – so it must be a planet. Looking out into the universe, planets are usually found to orbit stars, whatever their type, so what happened to PSO J318.5-22? Could it have broken away from its star after being ejected or, even more oddly, formed alone?