Go Home, Pluto’s Moons, You’re Drunk


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Go Home, Pluto’s Moons, You’re Drunk

Why the dwarf planet’s smaller moons can’t settle down.

Pluto's spinning moons. Video: NASA.gov/YouTube

Most moons in our solar system are tidally locked to their respective planets, keeping one side facing the planet. But Pluto's moon system, it turns out, isn't interested in playing the synchronous rotation game.

The above NASA animation depicts Pluto and its largest moon Charon in the traditional planet-moon formation, while the other four moons spin around like lunatics.

This model is based on data acquired during the New Horizons flyby, and reveals that Pluto's most distant moon Hydra—color-coded blue—rotates a dizzying 89 times per orbit. Scientists think that these outer moons behave so erratically because "Charon exerts a strong torque that prevents each small moon from settling down into synchronous rotation," according to a NASA statement.

That's so Charon. Always hogging the Plutonian spotlight.

No doubt more revelations are on the way as New Horizons continues to send along data and images from its encounter with Pluto and its oddball moons.

"It's hard to imagine how rapidly our view of Pluto and its moons are evolving as new data stream in each week," Alan Stern, the principal investigator for New Horizons, said in a statement. "As the discoveries pour in from those data, Pluto is becoming a star of the solar system."