rather than a head-on, collision with another planetary body. “The formation of Sputnik Planitia provides a critical window into the earliest periods of Pluto’s history,” said Adeene Denton ...

When did Pluto become a planet? When Pluto was discovered by Clyde Tombaugh in 1930, scientists were searching far and wide ...

And in a way, he will too: Tucked aboard New Horizons is a small vial of Tombaugh’s ashes, a symbolic envoy that will sail by Pluto and head farther into the Kuiper belt, perhaps chasing down ...