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What If the Earth Had Two Moons? Paperback – 2 Aug 2011

4.3 out of 5 stars 3 customer reviews

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Product details

  • Paperback: 304 pages
  • Publisher: St. Martin's Griffin; Reprint edition (2 Aug. 2011)
  • Language: English
  • ISBN-10: 0312673353
  • ISBN-13: 978-0312673352
  • Product Dimensions: 14 x 1.7 x 21.6 cm
  • Average Customer Review: 4.3 out of 5 stars  See all reviews (3 customer reviews)
  • Amazon Bestsellers Rank: 600,269 in Books (See Top 100 in Books)

Product Description

Review

"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 "What""If 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"

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 "What""If 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""

About the Author

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

Customer Reviews

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Top Customer Reviews

Format: Hardcover
if you are interested in what it would be like if things had turned out differently on our planet, then this is the book for you. lots of scenarios that would be good and bad for life on earth. two moons, large moon, captured moons, larger earth, etc. very interesting. well written and easy to follow. i enjoyed it.
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Format: Hardcover Verified Purchase
It's really fascinating seeing a scientist work through the logic of how the Earth might have been different. Each speculation begins with a bit of fiction - none of them very good, for my taste. But the science that follows is fascinating. Why it is unlikely two moons would have persisted if they had formed, but we could have got a second moon by capture. Or been a moon ourselves. Or developed 15 billion years in the future.
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Format: Hardcover Verified Purchase
This is certainly one for the nerdy science types. It is all speculation but very thought provoking and certainly worth the time to read. One for the sun-lounger / hammock / bathtub.
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Most Helpful Customer Reviews on Amazon.com (beta)

Amazon.com: HASH(0x8d9034ec) out of 5 stars 21 reviews
25 of 26 people found the following review helpful
HASH(0x8dac6774) out of 5 stars A good puzzler..... 22 April 2010
By Robert Busko - Published on Amazon.com
Format: Hardcover
What if the Earth Had Two Moons?: and Nine other Thought-Provoking Speculations on the Solar System by Neil F. Comins is one of the more interesting books I've read so far in 2010. As an amateur astronomer a few of the questions covered by Comin's wondering imagination aren't new. What is new, at least for me, is his ability to logically work through to a sensible conclusion. Given the range of possibilities covered in What if the Earth Had Two Moons the reader gets a glimpse of an active imagination in operation.

Specifically, the questions asked and answered are:

What if the Earth had two Moons?
What if the Earth were the moon of a massive planet?
What if the Earth orbited a less massive sun?
What if the Earth had a thicker crust?
What if the Moon orbited the Earth in the opposite direction?
What if the Earth had two Suns?
What if the Earth had a twin orbiting on the opposite side of the Sun?
What if the Andromeda Galaxy collides with the Milky Way? (Apparently this one is really going to happen at some distant point in the future.)
What if the Earth formed closer to the center of our galaxy?
What if the Earth formed in the distant future?

What if the Earth had Two Moons is certainly entertaining and quite educational.

If you're curious about any of these questions or just have a love of our physical environment then you'll want to read What if the Earth Had Two Moons.

I highly recommend.

Peace to all.
8 of 8 people found the following review helpful
HASH(0x8e0d3114) out of 5 stars Excellent! Illuminating! 15 Aug. 2010
By R. Geller - Published on Amazon.com
Format: Hardcover Verified Purchase
This is an excellent book! Very well written - I can't set it down. This is one of the most unique, interesting, and valuable books I have read in astronomy and geology. Many deep insights are gained simultaneously by asking "What If?".

Just as an example from the first few chapters, we take our tides for granted. Most of us know tides are related to the Moon, but we might not think the effects are significant enough to understand the topic in any detail. This book shows that nothing could be further from the truth. The effects are significant, and could have been very different for the different moons considered in this book. Only by considering a variety of possible moons (and different home planets) can we really appreciate our tides and what they could have been. You'll understand how our own tides have slowed down Earth's rotation and flung the Moon into a farther orbit. You'll understand how different conditions could have lead to stopping the Earth's rotation and a moon that gets torn apart by Earth and rains down debris to the planet's surface. That could have been us!

But, this book sheds light on a lot more than tides. By considering different possible earths and moons, we can also appreciate volcanoes - the ones we have, and the ones we're lucky we don't. Tremendous insight is gained by this approach, and leaves the reader in awe at - you guessed it - the world we live in, and what it might have been. Many core pieces of our past and present are woven together and elucidated in this book: the oxygen we breathe, the water life depends on, the plate tectonics that drive geology, and the evolution of life itself. And what if our Sun had different properties, or we orbited two suns instead of one (and many stars are in such pairs)? Few books can bring so many topics together, and elucidate them all at once. And, in such an enjoyable read.

There are different types of speculation. The speculations in this book are based on our best understanding of astronomy, geology, and biology. Some of the scenarios in this book might better be termed as extrapolations, and in this sense they are on more solid ground than mere speculations. This is important to appreciate because this book will expand your understanding of our world. The author also tells you the parameters that go into the astronomical models, and even better, why other choices (say, for masses and distances) might be dead-ends for any interesting phenomena. If you enjoy astronomy, some of these scenarios actually exist in similar ways elsewhere in our solar system, so you'll understand more about many actual planets and moons.

The book has no equations and is very accessible. Educators, students, and the wider public will all find this book an excellent read.
5 of 5 people found the following review helpful
HASH(0x8da6f7d4) out of 5 stars Great side reader for astronomy and physics courses 9 Nov. 2010
By electron0511 - Published on Amazon.com
Format: Hardcover
The title does not fully convey the breadth and depth of the material this book covers. By asking a series of seemingly innocuous "what if" questions like "what if the Earth had two moons?" the author introduces the reader to the frontiers of cosmology, astronomy, planetary science, as well as basic physics that govern all the processes involved. You will learn about how the universe and all the elements in it were created and how those elements ended up in the Earth (and you for that matter), how spiral galaxies form and what happens when two of them collide, how Earth ended up with a solid crust covered by oceans and an oxygen rich atmosphere, and much much more.

Each chapter is preceded by a short, entertaining, pseudo-scifi type story describing events unfolding on an alternate "Earth" under each "what if" scenario, followed by a detailed scientific analysis of what would really happen. Particular attention is paid to whether each scenario would allow for sentient life to evolve on the alternate "Earth," highlighting how life on our Earth may not have evolved the way it has had certain conditions been even slightly different.

The book may not be an "easy read," as some reviewers have stated, especially if you are unfamiliar with various science concepts such as plate-tectonics, globular clusters, planetary nebulae, solar winds, etc.(A glossary of terms would have helped, but then, you can look up all these terms on the web.) However, you learn so much from reading this book that it is well worth the effort.

This book would be a great side reader for any astronomy or physics course. In fact, there is so much information in it that it can potentially be used as the textbook proper. All physics and astronomy students should read this book so that they get a feel of how the simple laws of physics conspire to create the vast and intricate universe around us, and how lucky we are to exist at the right time and place to be able to see and appreciate it. All science fiction fans should also read this book if they are to properly speculate about the possibility of extraterrestrial life.
1 of 1 people found the following review helpful
HASH(0x8e0d3ab0) out of 5 stars Thought provoking 8 Jan. 2012
By Amazon Customer - Published on Amazon.com
Verified Purchase
This is a second book of this type for the author. In this book, he imagines additional scenarios in which an earth-like planet or Earth finds itself with some different variable. Each chapter changes the situation somewhat. In one chapter he imagines Earth with two moons. In other chapters he discusses ideas such as Earth being a moon of a larger planet, Earth being in a different part of the galaxy, Earth having a smaller sun and so forth. each chapter follows a similar format. They begin with a fictional story of some characters on the imagined planet in some situation that involves the difference being looked at and then the chapters go on to discuss the scientific and practical ramifications of the difference if it were really to be the case. In a number of cases, he discusses some basic astronomy issues such as the life cycle of stars or the makeup of galaxies.

This is a very interesting book because it makes you think not only about intriguing possibilities for other Earth-like arrangements, but also the actual situation of Earth itself. In a way, this book is sort of an attention-grabbing way of teaching astronomy by using interesting fictional scenarios to teach real-world issues. The reader not only learns about Earth's past, which involved very different things like molten crust, shorter days and huge tides, but also about the kinds of places life might be able to develop elsewhere in the universe. Many of the chapters obviously involved a great deal of calculation and research to determine things like how long a day would be on such and such a planet or how high the tides would be. Obviously, much of the material is highly speculative. For example, who is to say how long it would take sentient life to evolve, if it ever would on a planet in a different environment? Additionally, the author intentionally sets up his fictional planets to be just right for life. With probably trillions of planets in the known universe, it's very possible that some of these scenarios actually exist somewhere, but the point of this book isn't so much to talk about actual situations as to teach about astronomical effects. In a way, the whole book is like a big serious of thought experiments.

Personally, I found the book to be something of a page turner. While there were some sections that got a bit bogged down in extended discussion of things like how long a day might last on such and such a planet, overall, there were enough interesting ideas to keep my attention. I have only one complaint about the book. Both the fictional stories and the chapters themselves ended somewhat abruptly. The little stories at the beginning of the chapters would end right at some crescendo leaving you to think the wrap-up would come, but it never did. It would have been nice if the author had eventually gotten around to making reference to his stories later in the chapter or wrapping up what happened, but he leaves us hanging. Also, a number of the chapters just sort of end when a bit more of a summary would have been nice. These two things detract slightly from the effectiveness of the book. I think the stories and the chapters themselves would have been a bit more memorable had there been more resolution and summary. Because of this, I give the book 4 stars. If you are interested in astronomy, space, the evolution of life on earth or the potential for life on other planets, you will most likely enjoy this book. It injects the curiosity of a science fiction piece into the reality of the universe we live in.
1 of 1 people found the following review helpful
HASH(0x8e0d3b88) out of 5 stars Scientific Chinese food... 19 Nov. 2011
By John Me Wallace - Published on Amazon.com
Neil F. Comins has always been a mixed bag. Having read many of the original articles in "Astronomy" magazine that he later expanded in "What If the Moon Didn't Exist?", the briefer articles are often better through their concision. At chapter-length, I find myself getting a "just the facts, please" attitude, and that's no good. Yet, WITMDE has been a favorite read of mine ever since it was released.

Perhaps my criticism is not entirely fair. As a book that's exactly about its title, it's a fine, fun, and easy read, one that will appeal especially to SF fans and world-builders. Some have criticized this book for being overly technical, an assertion I vehemently disagree with; this book is so clearly aimed at neophytes that those with even an informal knowledge of geology and astrophysics will probably be left hankering for more scientifically rigorous fare. Furthermore, better organization and abundant illustrations make this work an improvement on its predecessor, overall.

The book falls short of perfect, less for the few glaring typos than for what the author chose to write. For instance, the Dichron chapter feels unfairly truncated, while the Futura chapter contains a long digression on the mechanics of interstellar colonization that, if it belongs in the text at all, should have been in its own chapter. The vignettes at the beginning of each scenario, though well-meant, are distracting.

Stylistically, I'd give the book three and a half stars if I could, but four is more honest; for all its flaws, it's enjoyable enough to win most people (myself included) over. And, if you haven't read WITMDE, get to it; it's a companion piece in every sense of the word.
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