A month long ecological event on Venus. Aphrodite Ocean turns green with spores, and the seas become a feeding frenzy.
A phenomon occurring every few thousand years, where the world is submerged in darkness.
The evolution of a star often kills off its orbiting celestial bodies.
One half of a sapient species. Souls are the half of a being that does not enter the afterlife; instead, they float into space and make up stars.