@freemo

WHAT IS A PLANET, and what isn't?

In August 2006, however, the International Astronomical Union announced that Pluto would no longer be considered a planet, due to new rules that said planets must “clear the neighborhood around its orbit.” Since Pluto’s oblong orbit overlaps that of Neptune, it was disqualified. -- see https://www.history.com/this-day-in-history/pluto-discovered; and see Wikipedia "IAU definition of planet" https://en.wikipedia.org/wiki/IAU_definition_of_planet