Unlike the scores of novels, films, and television miniseries that dwell on how humanity might deal with such an event, this novel takes us past the terrible collision and far into the future, with a group of people who escape the debacle to establish a safe harbor on Earth's Moon.

From Tycho Base they can monitor conditions on the devastated earth. Years pass, then centuries, and then millenia, as they, their cloned children, and their children's children through successive generations undertake the enormous challenge of restoring life to a barren planet.