Eris
Astronomers at Palomar Observatory discover a body beyond Neptune’s orbit that initial observations show is larger than Pluto. Eris is quickly dubbed the tenth planet by the media and the scientific community, and it is later found to have a small moon of its own in a close orbit, which is later named Dysnomia. But events overtake Eris and Dysnomia before the science textbooks have a chance to be rewritten to include a tenth planet: Eris becomes a case study in an ongoing debate within the International Astronomical Union about the definition of a planet. In 2006, the IAU will establish a set of parameters which determine that Eris isn’t a planet – and then rewrites the history books by deciding that Pluto isn’t either.
Voyager 2 at 10000
Launched ahead of its identical twin, Voyager 1, in 1977, NASA’s Voyager 2 spacecraft surpasses its 10,000th day in deep space. At 11 billion miles from Earth, Voyager 2 is one of the most distant human-made objects in space, surpassed only by Voyager 1. Both Voyagers are expected to function well into the 2020s, and are expected to have left the solar system to enter interstellar space by then.