Sci-fi novel about a world-destroying cataclysm from the 70s or earlier

Question

I remember reading a sci-fi novel back in the mid 70s in which the Earth was threatened by some sort of geological or astronomical catastrophe - can't remember if it was a collision from another celestial body or super earthquake or such, but the Earth could be "split in two". About the only detail which stood out in my mind played upon my juvenile sensibilities about sex and sexuality. As disaster loomed, a couple somehow involved in an effort to preserve the human species were at some point dressed in transparent clothing (uniforms, survival suits, or something). At the time it seemed rather racy, in hindsight it might have been something thrown in entirely gratuitously by the author. Anyway, if I recall correctly, the story ends with this couple being among the few survivors left to repopulate the planet.

(additional)

I have an uncertain recollection of a title something along the lines of "Worlds in Collision" or "When Worlds Collide", but Googling turns up either non-fiction or stories which don't seem to fit.

Can anyone identify the title/author of this story?

Answer 1

This is a long shot, but I wonder if it's When Worlds Collide by Philip Wylie and Edwin Balmer.

Annoyingly I can't find my copy (though I have found the sequel After Worlds Collide, which isn't much help!) but your description rings a bell in my memory, and it does match your recollection of the title. The Wikipedia article I've linked will hopefully give you enough detail for you to decide if this is the book you remember.

Answer 2

There are some points of similarity with Fritz Leiber's 1964 novel The Wanderer. The Earth is tidally wrecked by a steerable planet that gets too close (the titular Wanderer). There's plenty of sex in this book but I don't recall it being done to save the species, which might be a vote against this book, if you are sure that is in there.

In this book the Moon does get split in two, but not the Earth.

I enjoyed this book back in the day, but I don't think it has aged well.

Answer 3

Cataclysm: The Day The World Died, by Don Pendleton (1969)

An ecological crisis has worn away the world and on the horizon looms the devastation of all civilization