Includes bibliographical references (p. [273]-274) and index.
Contents:
What if the Earth had two moons? : Dimaan, Lluna, and Kuu -- What if the Earth were a moon? : Mynoa and Tyran -- What if the moon orbited backwards? : Anillo -- What if the Earth's crust were thicker? : Dichron -- What if the Earth formed fifteen billion years from now? : Futura -- What if there were a counter-earth, a planet in Earth's orbit on the other side of the Sun? : Dopple I, II, and III -- What if the Earth had formed elsewhere in the galaxy? : Kern I and II -- What if the Sun were less massive : Dimune I and II -- What if the Earth had two suns? : Zweisonne I, II, and III -- What if another galaxy collided with the Milky Way? : Earth.
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