If you’re like us, you grew up with a solar system that had nine planets in it. You also grew up in world that didn’t teach new math, but that’s a rant for a different day. Then one day they suddenly decided that designating Pluto as a planet was just wrong, and our most distant friend in the solar system suddenly was told he wasn’t good enough for the planet club anymore, and would forever be considered a ‘dwarf planet’. Kind of a consolation prize for those not cool enough for the big planets club. Pluto Day celebrates the discovery of Pluto in 1930, when it was designated as a planet, and that’s how it should have stayed!