After New Horizons streaked past Pluto in 2015, its main task was over, but it still had work to do. On New Year’s Day of 2019, it made a flyby of another, even more distant object named 2014 MU69, more commonly called Ultima Thule. Since then, the spacecraft has been slowly but steadily sending streams of information back across the increasingly vast gulf of space between it and Earth.

From that information, scientists now know that the snowman-shaped space rock formed from a gentle coll