Seveneves

When Neal Stephenson goes into space, he goes in style. The book is actually three almost separate books (I have a feeling that any other writer would have offered this as a trilogy, rather as a single narrative), and the scale of things is breathtaking.

The moon is broken up by an unknown agent, and the Earth must look forward to a five millenia long bombardment. Humanity tries to survive in any way possible, via space, underground and underwater. All scenarios are almost doomed from the start, but there is hope still. Humanity bounces back from a handful of humans to once again, tentative masters of their domain.