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| Pluto System |
Only one of the five moons has anything resembling a normal rotation.
If New Horizons
has taught us anything, it's that Pluto is one of the weirdest objects
ever explored by NASA, and that it's system is no less chaotic. But a
recent NASA demonstration displays just how chaotic its moons are. It's
moons don't so much "revolve" as "spin like they're in a free-fall."
Charon,
Styx, Nix, Hydra, and Kerberos all likely came from the same ancient
collision, and recent research suggests that at least three if not four
of the smaller moons are contact binaries formed when two or more moons
consolidated into one oddly shaped object.
But
while Charon, like many large moons in the solar system, faces the same
side of Pluto. Pluto is similarly tidally locked to it, and rather than
Charon orbiting Pluto, both orbit a common center of gravity
(barycenter) well outside either object. Thus, some consider it less a
moon, and more of a binary dwarf planet.
But
the other moons ... well, they do whatever they want, more or less.
They also orbit the barycenter, but aren't tidally locked. Two of them,
Nix and Hydra, have days that aren't even the same length, spinning at
different rates at different times. Kerberos and Hydra have faster rates
than the other moons, with Hydra spinning rapidly like a never-ending
top. Part of the reason may be that Pluto and Charon are so small that
they haven't pumped the brakes on the rapid spins of the moons since
formation.
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