Tuesday, June 9, 2015

Pluto's Moons Spin Unpredictably in Orbit

This image from the Hubble Space Telescope shows Pluto and its five known moons. The New Horizons team plans to study the moons during July's Pluto flyby. L. Frattare / STScI / NASA / ESA
This Hubble Space Telescope image shows Pluto and its five known moons. The New Horizons spacecraft will study Pluto’s moons during its July, 2015 flyby.
(Image Sources: L. Frattare / STScI / NASA / ESA.)

If you lived on one of Pluto’s small moons Nix or Hydra, you’d have a hard time setting your alarm clock. That’s because you couldn’t know for sure when, or even in which direction, the sun would rise. This is a surprising result of new observations of the Pluto-Charon system published in the journal Nature, and it’s illustrated by a new computer animation (Internet link to new computer animation at end of this blog post).

Charon, Pluto's largest moon, is much larger than the other moons and more than half the size of Pluto.

In the animation, Pluto’s moon Nix changes its spin unpredictably as it moves through space, orbiting the double world Pluto and its largest moon Charon. The view is from the surface of Pluto as Nix circles the Pluto-Charon system. This is a time-lapse view of the moon, compressing four years of motion into two minutes, with one complete orbit of Pluto-Charon every two seconds (in contrast to the actual orbital period of 24.9 days).

The animation comes after comprehensive analysis of all available Hubble Space Telescope data showing that two of Pluto’s moons, Nix and Hydra, are wobbling unpredictably.

Scientists believe the other two small moons, Kerberos and Styx, are likely in a similar situation, pending further study.

John Grunsfeld is associate administrator of NASA’s Science Mission Directorate in Washington, D.C. He said:
Hubble has provided a new view of Pluto and its moons revealing a cosmic dance with a chaotic rhythm. 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 the chaos? Scientists say it’s because the moons are embedded inside a dynamically shifting gravitational field caused by the system’s two central bodies, Pluto and Charon, whirling about each other. The variable gravitational field induces torques that send the smaller moons tumbling in unpredictable ways. This torque is strengthened by the fact the moons are football shaped rather than spherical.

NASA's New Horizons spacecraft will get a closer view of the Pluto-Charon system, when the spacecraft flies-by the system next month.

More Including New Computer Animation:
Link >>> http://earthsky.org/space/plutos-moons-tumble-in-chaotic-dance

Source: EarthSky.org .

More on Pluto: Link >>> http://en.wikipedia.org/wiki/Pluto

More on Charon: Link >>> http://en.wikipedia.org/wiki/Charon_%28moon%29

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