What If the Earth Had Two Moons? And Nine Other Thought-Provoking Speculations on the Solar System

"What if?" questions have always stimulated people to think in new ways. What if the Earth Had Two Moonsleads us on a fascinating 10 world journey exploring what the Earth would be like if conditions in the universe were slightly different. The answer: Earth would be different, often in ways that would surprise us. The title chapter, for example, gives us a second moon orbiting closer to Earth than the one we have now. The night sky is a lot brighter, but not forever. Eventually the moons collide, with one more-massive moon emerging after a period during which Earth has a Saturn-like ring. The scenarios also shed new light on the burgeoning search for life on planets orbiting other stars.Appealing to adult and young adult alike, this book follows on the author's previous bestseller, What if the Moon Didn't Exist?,with completely new scenarios backed by the latest astronomical research.

NEIL F. COMINS is a professor of physics and astronomy at the University of Maine and author of popular scientific books, articles and textbooks.

"Armchair astronomers and hard SF fans who love a good game of cosmological What If? will find this an entertaining follow-up to physicist Comins's WhatIf the Moon Didn't Exist? Here he presents 10 more intellectual puzzles that explore new worlds, and imagine what life there might be like. Each chapter opens with a vivid glimpse of a hypothetical new world ... This is a lucid, thoroughly accessible presentation of what might have been that is sure to make this volume as popular as its predecessor."--Publisher's Weekly "Stretching his scientific imagination, Comins tweaks the astronomical dials that control evolution on Earth, such as the length of the day, the height of the tides, or plate tectonics ... An astronomy professor and author of several successful science books (What If the Earth Had No Moon? 1993), Comins plays out his scenarios in physics-grounded narratives that all posit the same result despite different evolutionary paths: the rise of humans. Depicted in fictional predicaments that preface each chapter, they, warming up Comins’ factual explanations, create sf crossover appeal for this entertaining piece of popular science."--Gilbert Taylor, Booklist