Astronomers discover a “twin” planet to the mysterious, long-predicted Planet Nine – Salon

Of all the planets that humans have discovered in other solar systems, most of them orbit close and tight to their parent star. That’s partially due to the selection effect: the easiest-to-spot exoplanets (meaning a planet outside of our solar system) are those that are close enough to their star (or stars).
Hence, finding a planet that orbits really, really far from its parent star is a rare occurrence — so rare, in fact, that it’s hard to do even in our own solar system. Indeed, there is much…

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