Planet 9(X): The History, Location & Orbit [2021 Update CalTech]

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  Planet 9 may be closer and easier to find than thought—if it exists (1 Sep 2021)
  by NADIA DRAKE, https://www.nationalgeographic.com/
  A new study’s “treasure map” suggests that a planet several times more massive than Earth could be hiding in our solar system, camouflaged by the bright strip of stars that make up the Milky Way.
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  Among the solar system’s more intriguing mysteries is whether a large, icy planet lives in the outer regions of our cosmic neighborhood, well beyond the orbit of Neptune. This hypothetical world, nicknamed “Planet Nine” by some of the scientists searching for it, has stirred up controversy since it was first proposed.
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  The unseen planet is predicted to exist based on its apparent gravitational influence on a group of small objects with odd, clustered orbits. But so far, searches for it have come up empty, and critics contend that the hints of its presence are just ghosts in the data. Now, a new analysis predicts that if it’s out there, that skulking planet could be closer, brighter, and easier to spot than previously estimated.
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  Instead of orbiting our home star once every 18,500 years, astronomers calculate that it loops around the sun in about 7,400 years. That tighter orbit brings it much closer to the sun than previously expected, which means that Planet Nine may appear brighter to Earth-based telescopes.
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  “I think it’s within a year or two from being found,” says Mike Brown, an astronomer at the California Institute of Technology and an author of the new study, which has been accepted for publication in the Astronomical Journal. But, he adds, “I’ve made that statement every year for the past five years. I am super-optimistic.”
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