Neil Stephenson’s Seveneves is one of those science fiction novels that invades your dreams and your subconscious. Days after you finish it, you find yourself thinking about it, and the implications of this scene or character or situation. Even finishing the book can be difficult; I found myself reading the last 100 pages at a snail’s pace, because finishing it meant I would have to stop reading. (Rereading, of course, is a possibility, but lacks the same sense of discovery).

It’s a somber book, appropriately, tragically heartbreaking. It’s also a book in love with technology. Stephenson has imagined his world so perfectly, you can sense his excitement over having created it. He’s not just interested in how stuff works, but also in what it looks like. A scene where a young woman waits for public transit to pick her up and deposit her somewhere else, that simple a scene, can be exhilarating. It’s also a book where, for the first two thirds, the title, Seveneves, makes no sense whatsoever, and thereafter makes perfect sense–is, in fact, the perfect title. And that moment of discovery comes at the moment of greatest despair, which also becomes the moment of greatest possibility.

And it’s a science fiction novel (or is speculative fiction the preferred label these days?), set entirely on Earth or in our planet’s general vicinity. It has space travel–a lot of space travel–but all of it close to home.

The basic premise couldn’t be more terrifying. Something, some Agent, splits the Moon. Shatters it. (The characters briefly speculate about the nature of the Agent, but without reaching any conclusions). The Moon, as it disintegrates, starts throwing off meteorites, which Earth’s gravity captures. Scientists (including one science expert character clearly modeled on Neil DeGrasse Tyson), calculate that it’s just a matter of a couple of years before all of the Moon comes crashing down, leading to catastrophe. In other words, the Moon’s destruction will wipe out all life on the planet Earth. If humanity is to be saved, it will have to be in space.

And so plans are made to build a large expansion onto the International Space Station. And to create smaller craft, which they end up calling ‘arklets’ for a group of young people, carefully selected from every culture on earth, representing earth’s diversity, with the ability to ‘swarm’ in order to dodge space rocks.

And in the meantime, we’re given time and space to imagine it; the ultimate Armageddon. The near-complete extinction of, not just the human race, but all life on Earth. It’s a staggering thought, shattering. Wisely, Stephenson allows us to experience it as we would–by showing the connections between a few characters and their immediate families. A woman and her fiancee; a man and his new wife; a young woman and her father and brothers. That’s how we would feel about it; that’s what the novel does.

I mean, we all come to this earth knowing that we’re going to die. But we do count on that three-score and ten. We want to make plans, excel at something, achieve, leave a legacy, if only a legacy of family and love and marriage. We are pretty well inured to dying. But life doesn’t strike us as hopeless. We do set goals, and take pleasure in achieving them. What if we were robbed of all that? What if we knew it was all going to end, for all of us. Strangely enough, as I read, I thought of Tom Lehrer, the great comic pianist/singer, and his cheerful, upbeat song about thermonuclear holocaust: “We’ll all go together when we go.” What if that were our reality? Still could be, obviously.

Could this work? Stephenson estimates that, after the initial bombardment, it would take Earth approximately 5000 years to cool down enough to sustain life again. Well, could humanity survive 5000 years in space? Could we work out some kind of artificial gravity, enough to keep bone density compatible with homo sapiens survival? Could we find shelter, from cosmic rays if not honking big pieces of moon rock? More to the point–and this is the saddest part of the novel–could we get along? Could we keep from killing each other? Could we survive mentally?

I don’t want to give away much in the way of spoilers. Suffice it to say that the novel seems both implausible and, just barely, possible. And it’s ultimately extraordinarily optimistic, even in the midst of terrible tragedy. That may be among it’s most remarkable achievements; that it’s ultimately kind of upbeat in tone.

I like science fiction. I also don’t keep up with the genre, and it may well be that there are ten other sci-fi novels out there as good as this one that y’all are going to tell me about. Still, this one is extraordinary. Just a superb read. Treat yourself.