"Countdown" is a book by Patrick Moore, the British amateur astronomer. As a teenager, I've read a Swedish translation of the original (1983) edition. There's apparently a much extended 2009 edition as well, which I haven't seen.
Moore takes us on an epic journey through Western end-times predictions, from the religious to the "scientific", with the inevitable cooks thrown in here and there. He's short on analysis - a scholar of comparative religion would go bonkers reading this - but at least the book is irreverently entertaining! The Millerites are prominently featured, alongside Velikovsky, the Welt Eis Lehre, the movie Star Wars and (surprise) the Aetherius Society. A chapter on astrology is included, and so is the so-called Jupiter Effect, which Moore himself was apparently involved in debunking.
Sometimes, the connection between Moore's whipping-boys and end-times predictions is pretty slim, and it's obvious that the author has really written a sequel to "Can you speak Venusian", a more general book about Independent Thinkers (read: cranks, pseudo-scientists and cultists). When I read "Countdown" years ago, I was somewhat stunned by Moore's claim to be a friend of George Adamski. How could a prominent British astronomer be on a friendly basis with a crackpot UFO contactee? Later, I learned that Moore is an *amateur* astronomer, popular science writer and media personality, which explains his rather strange pastimes. (But then, the Astronomer Royal Fred Hoyle had pretty strange pastimes, too! Archaeopteryx, anyone?)
"Countdown" should perhaps be taken with a certain grain of salt - Moore seems to have been something of a prankster, so who knows what he and Adamski were *really* up to, LOL - but as light reading on a weekend evening, it's excellent.
(This review is of the 1983 edition.)