NASA says Pluto's moons are 'tumbling in absolute chaos'

Imagine knowing the sun will rise everyday -- but never knowing when or where. On the moons of Pluto you just might have that problem.

Information gathered by the Hubble space telescope tells us Nix and Hydra, two moons of the dwarf planet, are embedded in a constantly shifting gravitational field. As a result, Nix and Hydra wobble and tumble unpredictably.

Pluto's other moons, Kerberos and Styx, are also two football shaped spheres, and behave much the same way.

The New Horizons spacecraft will collect new data and imagery as it flies by Pluto and its moons next month.