At just 23 years old, Tombaugh sent his drawings, unsolicited ... the discovery of a new planet. The search for Pluto did not begin with Clyde Tombaugh, to be fair. That distinction belongs ...

If you answered "Pluto's planethood," your grasp of the astronomical is excellent. Feb. 18 marks the 95th anniversary of the discovery of our outermost planet-not-planet. Here's what to know about the ...