Impact from a space rock may have helped shape Pluto’s heart

OXON HILL, Md. — Pluto’s got a roughly 4-billion-year-old case of heartbreak. The left ventricle of the dwarf planet’s famous heart-shaped feature might owe its existence to a run-in with a big space rock, planetary scientist Paul Schenk reported November 10 at the 47th meeting of the American Astronomical Society’s Division for Planetary Sciences.

The region, informally called Sputnik Planum, is an 825-kilometer-wide, 4-kilometer-deep basin, said Schenk, of the Lunar and Planetary Institute in Houston. And except for some erosion to the south, the basin is roughly circular, which is typical for other impact craters in the solar system. If an interplanetary interloper is at fault, it would have smashed into Pluto at least 4 billion years ago. “It’s difficult to explain by other mechanisms,” Schenk said.