Hubble Reveals 'Cosmic Dance' of Pluto's Wobbly Moons

Two of Pluto's moons, Nix and Hydra, are wobbling unpredictably in some kind of "cosmic dance," according to new data discovered by NASA's Hubble Space Telescope, adding more mystery to this former planet.

According to scientists, if you lived on Nix or Hydra, you'd have a hard time setting your alarm clock. That's because you could not know for sure when, or even in which direction, the Sun would rise. And based on Hubble's new comprehensive analysis, they believe the other two small moons, Kerberos and Styx, are likely in a similar situation, pending further study.

"Hubble has provided a new view of Pluto and its moons revealing a cosmic dance with a chaotic rhythm," John Grunsfeld, associate administrator of NASA's Science Mission Directorate in Washington, DC, said in a statement. "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."

So what makes Pluto's moon so topsy-turvy? It is reportedly because the moons are situated inside a shifting gravitational field, which is created as the system's two central bodies, Pluto and Charon, rotate around each other. This phenomenon induces torques that send the smaller moons tumbling erratically. And since the moons are football-shaped rather than spherical, this torque is strengthened.

"Prior to the Hubble observations nobody appreciated the intricate dynamics of the Pluto system," noted Mark Showalter, who conducted the Hubble research. "Our report provides important new constraints on the sequence of events that led to the formation of the system."