You might think you know a thing or two about Pluto’s (renamed) Sputnik Planitia, the ice-filled, heart-shaped basin that starred in hundreds of New Horizons images this summer. But it turns out that Pluto’s heart is heavy—so heavy that it may have made the dwarf planet tilt about 60° over millions of years, Smithsonian reports. In two studies published this week in Nature, scientists reveal how the basin may have formed when an asteroid bombarded the dwarf planet’s surface billions of years ago. Then, nitrogen ice collected in the basin, perhaps supplemented by waters from an underground ocean, moved Pluto’s center of gravity. That extra weight was enough to roll the planet over, locking Pluto into a stand-off style orbit with its moon, Charon, and sending cracks rippling across the surface of the dwarf planet. But the only way to know for sure is to send a satellite into Pluto’s orbit to measure its gravity—something that won’t happen for a long time yet.
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