The Coming — Joe Haldeman

Astronomy professor Aurora `Rory' Bell gets a message from space that seems to portend the arrival of extraterrestrial visitors. According to her calculations, whoever is coming will arrive in three months--on New Year's Day, to be exact.

A crowded and poisoned Earth is moving toward the brink of the last world war--and is certainly unprepared to face invasion of any kind. Rory's continuing investigation leads her to wonder if it could be some kind of hoax, but the impending 'visit' takes on a media life of its own. And so the world waits. But the question still remains as to what, exactly, everyone is waiting for...