In the first line of Seveneves, Neal Stephenson lays out the event that the entire book’s action revolves around:

The moon blew up without warning and for no apparent reason.

Mild spoilers, but fairly quickly, scientists in the book figure out that this is a very bad thing that will cause humanity to become extinct unless drastic action is taken.

In the novel, one day the moon breaks up into 7 roughly equal-sized pieces. These pieces continue peacefully orbiting the Earth for a while, and eventually two pieces collide. This collision causes a piece to fragment, making future collisions more likely. The process repeats, at what Stephenson says is an exponential rate, until the Earth is under near-constant bombardment from meteorites, wiping out (nearly) all life on Earth.

Jason Cole wondered how plausible that scenario is and created a simulation to model it. Turns out Stephenson had his figures right.