Explanation:
Why is this moon shaped like a smooth egg?
The robotic Cassini spacecraft completed the first flyby ever of Saturn's small moon
Methone
in May and discovered that the moon has no obvious craters.
Craters, usually caused by impacts, have been seen on every
moon,
asteroid, and comet nucleus
ever imaged in detail -- until now.
Even the Earth and
Titan have
craters.
The smoothness and egg-like shape of the
3-kilometer diameter moon might be caused by
Methone's
surface being able to shift --
something that might occur were the moon coated by a deep
pile of sub-visual
rubble.
If so, the most similar objects in our Solar System would include Saturn's moons
Telesto,
Pandora,
Calypso, as well as asteroid
Itokawa,
all of which show sections that are unusually smooth.
Methone
is not entirely featureless, though, as some surface sections
appears darker than others.
Although flybys of Methone are
difficult, interest in the nature and
history of this unusual moon is sure to continue.
