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Yes, Pluto is the tenth planet. To discover Planet 9, simply open your ephemerides and look for "Neptune".

• db48x 1y ago
  Back in the day Mercury, Venus, Earth, Ceres, Pallas, Vesta, Juno, Mars, Jupiter, Saturn, Uranus, and Neptune were the 12 planets. You could kinda consider Pluto to be the 13th planet, but in 1930 when it was discovered there were already over 1000 named asteroids. So Pluto is the 1146th planet.
  • juped 1y ago
    Pallas and Vesta aren't gravitationally rounded, though. But then again, the Moon is (being much larger than Ceres). (It's just better numbered as planet 3-1.)
    • db48x 1y ago
      That wasn’t a requirement in 1930.
      • juped 1y ago
        It is required by me, now!