Hubble Finds Tiny Pluto's Moons are Chaotic Tumblers

or the most part, Pluto’s four small moons appear to orbit harmoniously and precisely around the equatorial region of the dwarf planet, but appearances can be deceiving.

A new analysis of Hubble Space Telescope images shows that at least two of the moons, Nix and Hydra, wobble constantly and unpredictably, the result of orbiting not just Pluto, but its cosmic companion, Charon.

“Their mutual motion creates a time-variable and distinctly asymmetric gravity field,” that in turn makes the outer moons’ orbits wobble, astronomers Mark Showalter, with the SETI Institute in Mountain View, Calif., and Douglas Hamilton with the University of Maryland, write in this week’s Nature.

Complicating the cosmic waltz are the odd, football shapes of the small moons. Scientists suspect sibling moons Kerberos and Styx are in similar situations.

The research is expected to flesh out details about the events that led to the formation of the solar system and provide insights about how similar systems form around other stars in the galaxy.

Scientists will get their first close-up look at Pluto and its entourage when NASA’s New Horizons spacecraft sails by next month.

From Discovery News