3. Miranda's Frankenstein Appearance
The smallest of Uranus' five major moons, Miranda looks like a Frankenstein world, stitched together from distinct pieces into some misshapen monstrosity. This patchwork appearance to the moon's surface suggests intense geological activity in its past that led to broken terrain, huge canyons that crisscross, and large, concentric grooves called "coronae."
However, at one-seventh the size of Earth's moon, Miranda is too small to have been tectonically active. So how do we explain all these features?
One belief is that Miranda's orbit was more oval in the past, resulting in a larger difference between the points at which it is closest and farthest from Uranus. When it is further from Uranus, the planet's gravity tugs at it less powerfully than when it is closer, leading to tidal flexing that deforms the moon and warms its interior through friction. Another theory is that Miranda - or rather, pre-Frankenstein Miranda - was shattered by a massive impact, and the pieces reassembled into the current, bizarre shape.