This book is "Big."
Same ground as "Deep Impact", and "Meteor", and that Bruce Willis film that best remains nameless, but Mr. McDevitt takes a Tom Clancy approach and has the comet destroy the moon instead of the earth with the fall out of the moon debris being dealt with with a cast of wonderful, well written characters, and a plot that keeps you at the edge of your seat to the very last page.
I've rarely read better fiction than what Jack McDevitt is putting to paper. Almost every book has it's own unique style and so far, they all are wonderful!
This wasn't the case. First off, Jack McDevitt's strength lies in his characters. There are a wonderful range of characters in this book, and you don't have a clue who will survive. That's another strength: the plot is not predictable, and the mortality rate is plausible given what is going on.
Set slightly ahead in the future, man has finally opened a base on the moon - just in time for the moon to be in the way of a high-speed meteor. Spotted by accident by an amateur astronomer (one of the only overdone "Seen-it-before" moments of the book), there's a kind of panic pace to the first half of the novel as the people of the moon try desperately to get back to earth and the orbital stations that support the colony.
The second half of the book deals with the fallout - having the moon shattered is even worse than the single meteor, as now the shards of the moon are threatening to fall from the sky...
Throughout this high-paced background however, it is the characters who shine through this novel. It was the first McDevitt I'd read, and it launched me on a McDevitt jag for quite a while after. Give it a shot - there are no Aerosmith soundtracks to make it hurt.