Pluto’s heart-shaped splotch, Tombaugh Regio, likely arose from an ancient collision with a 700-kilometer planetary body early in the dwarf planet’s life, according to a study in Nature Astronomy. The study used smoothed particle hydrodynamics software to build numerical simulations that indicate the combination of Pluto’s core frigidity, the slant of the impact and its relatively low velocity left behind the Sputnik Planitia, a deep basin that harbors much of Pluto’s nitrogen ice.

Full Story: CNN (4/18)