Dirty Snowballs Older Than Earth

Right now, one is falling toward you. Not metaphorically — a dirty snowball the size of a city, older than the ground under your feet, older than the oceans, older than the Moon. It has been waiting in the dark for four and a half billion years. Then something nudged it — a passing star, maybe, or the slow gravitational breath of Jupiter — and it began to fall. It will take thousands of years to arrive. You will not be here to see it. But when it does, the Sun will burn off its skin, and for a few weeks it will grow a tail a hundred million kilometres long, visible from the ground to anyone who happens to look up on the right night. People have always looked up on those nights. They have always felt the same cold certainty: this is a sign. A comet appeared before Caesar died. Before the Norman conquest. Before the Flood, in some older stories. They were not wrong to feel it. They just didn't know what it was signing. A comet is not a message from the gods. It is a piece of the original solar system — the raw material left over from the moment the Sun first turned on — arriving late, trailing fire, as if it forgot to be there at the beginning.