It was a New Year’s Eve like no other. First of all, the big celebration started a half hour after midnight. Children were waving mini-flags, surrounded by throngs of giddy planetary scientists. And four billion miles away, one billion miles past Pluto, the New Horizons spacecraft was flying past an enigmatic object called 2014 MU69–better known by its nickname, Ultima Thule.
When radio signals from New Horizons finally reached Earth the next morning, they revealed that the mission was a smashing success. The first images of MU69 showed that it is a double-lobed object, apparently created from the delicate joining of two primitive planetary building blocks, or planetessimals. It was everything the mission scientists had hoped for. The only thing that felt off about the triumphant event was the object’s name: not only because some people objected to the Nazi mythology attached to Ultima Thule, but because of the name’s literal meaning of “beyond the known world.”
