Ultima Thule, an icy world 4 billion miles from the sun, looks like a big snowman. At a news conference on Wednesday, scientists working with NASA’s New Horizons mission released several images that the spacecraft took as it flew by on Jan. 1.
The scientists now say with confidence that Ultima Thule long ago was two bodies that got stuck together, what they call a contact binary. “Two completely separate objects that are now joined together,” said S. Alan Stern, the principal investigator for the mission.