Was it an asteroid? A nuclear war? A huge volcano? The author never says what caused the lingering winter which blocks most of the sun's light and covers everything with ash - even the snow is gray. Nothing grows, and the few remaining human survivors wander the barren land searching for anything that will keep them alive a little longer. It's grim and dark in more ways than one.
Although I'm not obsessed with post-apocalyptic fiction, I have read a number of books in this genre over the years. While we hope and work to avoid the end of life as we know it, it is interesting to think about what it would be like, and about the survivors and how they would cope. Some of the best I've read include Riddley Walker, The Wild Shore, and Oryx and Crake. I now have to add Cormac McCarthy's The Road to that list.
This book was on many "best of" lists for 2006, and was recently added as a rather unusual selection for Oprah's Book Club. It's not really so much a science fiction novel as it is a story of parental love and devotion, and of decency amid horror. The descriptions of the destroyed Earth are amazingly realistic - you can see and even taste and smell this world. As scary and sad as it is, the book is wonderfully written and is a compelling page turner - I finished it in two evenings.
There's not really any connection to space in this book, except in one scene where the boy and his father are discussing whether there still might be people alive in other places. He asks about Mars. The father says, if you had a really good spaceship and people to help you, maybe you could go. The boy asks, would there be food and stuff when you got there, and the father says, no, there's nothing there.
Maybe we could change that part.