New Images of Pluto's Moons Reveal Chaotic Behaviors

Researchers have taken a closer look at Pluto's moons, Nix and Hydra, and have discovered some startling facts. A comprehensive analysis of all available Hubble Space Telescope data reveals that two of Pluto's moons are wobbling unpredictably.

"Hubble has provided a new view of Pluto and its moons revealing a cosmic dance with a chaotic rhythm," said John Grunsfeld, associate administrator of NASA's Science Mission Directorate, in a news release. "When the New Horizons spacecraft flies through the Pluto system in July we'll get a chance to see what these moons look like up close and personal."

Why are these moons so chaotic? They're embedded inside a dynamically shifting gravitational field caused by the system's two central bodies, Pluto and Charon, which whirl around each other. The variable gravitational field induces torques that send the smaller moons tumbling in unpredictable ways.

"Prior to the Hubble observations nobody appreciated the intricate dynamics of the Pluto system," said Mark Showalter of the SETI Institute. "Our report provides important new constraints on the sequence of events that led to the formation of the system. However, that does not necessarily mean that the system is on the brink of flying apart. We need to know a lot more about the system before we can determine its long-term fate."

NASA's New Horizons probe, which is due to fly by the Pluto-Charon system in July 2015, will help answer some of the questions about the Pluto system. These new discoveries, in the meantime, are showing scientists what they should focus on. Not only that, but the chaos in the Pluto-Charon system offers insights into how planets orbiting a double-star might behave.

"Pluto will continue to surprise us when New Horizons flies past it in July," said Showalter. "Our work with the Hubble telescope just gives us a foretaste of what's in store."

The findings are published in the journal Nature.

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