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What If the Earth Had Two Moons?: And Nine Other Thought-Provoking Speculations on the Solar System Hardcover – March 30, 2010

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Product Details

  • Hardcover: 304 pages
  • Publisher: St. Martin's Press; 1 edition (March 30, 2010)
  • Language: English
  • ISBN-10: 0312598920
  • ISBN-13: 978-0312598921
  • Product Dimensions: 6.4 x 1.2 x 9.6 inches
  • Shipping Weight: 15.2 ounces
  • Average Customer Review: 4.2 out of 5 stars  See all reviews (20 customer reviews)
  • Amazon Best Sellers Rank: #407,126 in Books (See Top 100 in Books)

Editorial Reviews

From Publishers Weekly

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, such as in the title scenario, where Earth's gravity captures a second moon—a scenario that ends in destruction. Equally disastrous would be an Earth with a thicker crust—unable to form new volcanoes, hot magma would simply burn through the crust's surface, melting continents and the ocean floor. In another scenario, our solar system forms 15 billion years later than it did, prompting Comins to conjecture that aliens would have more time to traverse great distances to the planet and colonize it. This is a lucid, thoroughly accessible presentation of what might have been that is sure to make this volume as popular as its predecessor. 25 b&w line drawings. (Apr.)
Copyright © Reed Business Information, a division of Reed Elsevier Inc. All rights reserved.

From Booklist

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. He adds a second moon; he converts Earth into a moon of a Neptune-like planet; he reverses the direction of the Moon’s orbit; he puts an additional Earth into Earth’s orbit; he moves the solar system to other locations in the Milky Way; and in an ostentatious display of omnipotence, Comins makes Earth 15 billion years in the future. On these alternative Earths, of which Comins describes 10 in total, the evolutionary environment changes markedly once the author hits the start button. 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

Customer Reviews

You'll understand how our own tides have slowed down Earth's rotation and flung the Moon into a farther orbit.
R. Geller
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.
Amazon Customer
All science fiction fans should also read this book if they are to properly speculate about the possibility of extraterrestrial life.

Most Helpful Customer Reviews

25 of 26 people found the following review helpful By Robert Busko VINE VOICE on April 22, 2010
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.
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8 of 8 people found the following review helpful By R. Geller on August 14, 2010
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)?
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5 of 5 people found the following review helpful By electron0511 on November 9, 2010
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.
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More About the Author

I was born in New York City in 1951. We lived in several towns throughout New York and New England as I was growing up. To give you an idea of how far we have come since then, in the early days of my childhood you picked up the phone and the operator came on and asked to whom you would like to be connected.

From an early age, I was fascinated by gravity and the nature of matter. In 1965, while in high school in Ardsley, New York, I proposed to a friend, SP, a fellow science geek, that different fundamental particles were just different vibrations of very thin strings. We discussed the idea over several ping pong games. Needless to say, I lacked the mathematical training to do anything with such ideas at the time.

At seventeen, I enrolled at Cornell in electrical engineering. Quickly tiring of teachers justify equations by saying, "scientists have shown that...", I transferred to the engineering physics program in order to learn the derivations of those equations. In 1969, still interested in the concept of particle strings, I presented the idea to my sophomore physics professor, who assured me that the notion (now superstring theory) was not worth pursuing. Only time will tell if he was right. I moved on to other interests, most notably general relativity (GR).

It was also during this time, while a midshipman in the Navy ROTC program, that I earned my army Airborne wings at Fort Benning and endured a hurricane at N.A.S. Corpus Christi, earning a letter of commendation for operating the base's ham radio station during the storm. I remember watching trucks slide sideways down the streets. I also became a private pilot during that period.

Finishing the required courses at Cornell in three years, my fourth year was filled with graduate courses, including notable ones taught by Hans Bethe and Michael Fischer.

After graduation, I earned a masters degree in physics at the University of Maryland, assisting with the first generation of gravity waves detectors, designed to detect gravitational radiation. Gravitational radiation can be visualized as ripples in the fabric of space that travel at the speed of light from their sources. It is predicted by the equation of Einstein's general relativity and has been observed indirectly, by observing pairs of orbiting objects that lose energy and thereby spiral closer and closer together. The energy they lose is emitted as gravitational radiation. Gravity wave detectors, when built with sufficient sensitivity, will be able to detect these waves directly and thereby enable us to explore aspects of astronomy we cannot otherwise examine, such as the early stages of the Big Bang event that created the universe, details of powerful stellar explosions, and the changing orbits of pairs of black holes and neutron stars, as mentioned above.

In the mid-1970s, I was privileged to be accepted as Bernard Schutz's first graduate student studying general relativity at what was then University College, Cardiff, Wales (now Cardiff University). During those years, which were a golden era of GR research, I presented some of my work to Stephen Hawking's group at Cambridge. I remember watching Stephen zooming around Cambridge in his motorized wheelchair. I also attended a dinner party at his home. Other memorable events during that time included attending memorable conferences on GR at Gregynog in central Wales and at an Ettore Majorana conference in Erice, Sicily; and visiting Roger Penrose's group at Oxford.

Skillfully guided by Schutz, I did work on the properties of neutron stars, some of which was cited by Subramanyan Chandrasekhar in his 1983 Nobel prize lecture.

Ever since I was 14, when we took a driving trip from NY, through Maine, to the Gaspe peninsula in Quebec, I wanted to live in Maine. I was fortunate enough to achieve that goal when, in 1978, I was offered a position on the faculty of the University of Maine Department of Physics and Astronomy. I have been here ever since. BTW, if you ever get a crossword clue: "Maine college town," the answer is Orono, home of the University of Maine.

I have a variety of interests in astronomical research. I and my students conduct work in:
- Observational astronomy, which I have done using optical telescopes in Arizona and the VLA radio telescope in New Mexico
- Computer modelling of galaxies like our Milky Way
- General relativity, including exploring original ways of creating black holes
- Human perception of the Sun and stars. (For example, the Sun emits all colors, with different intensities. Turquoise is its most intense color, so why does it appear yellow?)
- Astronomy education, including identifying thousands of common misconceptions people have about astronomy and ways to overcome them (See "Heavenly Errors," discussed below)

During four summers in the 1980s, I was at Stanford and worked at the NASA Ames research center at Moffett Field, CA, doing computer models of galaxies with Dr. Bruce F. Smith. My research in all the areas has led to the publication of several dozen papers.

My writing career began around 1980 when I wrote questions in science for a prominent testing service. This continued for several years and scores of questions. Then I wrote over a dozen articles for "Astronomy" magazine.

In 1990, when my older son, James, was five, he inundated me with "What if?" questions, which I did my best to answer. One day during this time, colleague David Batuski wandered into my office and announced that scientists look at the world "in to much the same way." Bad English, but I got his drift. Intrigued, I proposed that we try looking at it differently. We sat there for several minutes, trying to come up with alternative ways of "looking at the world." It wasn't easy. However, James's "What if?" questions percolated into my consciousness and I grabbed the first one about the world that I could formulate, namely "What if the Moon didn't exist?". Dave and discussed it for a few minutes, until a student came by to see him. I was hooked. By the end of the day, I had worked out the concepts presented in the title chapter of my first book, "What if the Moon Didn't Exist," (1993: HarperCollins).

"What if the Moon Didn't Exist?" has served as the basis for numerous TV and radio shows, as well as several planetarium shows, Mitsubishi's pavilion at World Expo Aichi, 2005, in Nagoya, Japan, and at the Huis Ten Bosch (pronounced 'house tem bosch') resort in Nagasaki. I reached one of the pinnacles of my career when I became a cartoon character in Japan, as a result of "What if the Moon Didn't Exist?".

The sequel to "what if the Moon Didn't Exist?", "What if the Earth had Two Moons?" (2010:St Martin's Press) is now out and, I am pleased to note, "What if the Moon Didn't Exist?" is back in print!

In 1995, author and astronomer William J. Kaufmann, III, died and I took over writing his college textbook "Discovering the Universe." My first edition was wildly successful and it became, my editor at WH Freeman & Co. told me, the best selling astronomy text in the world. This led to several more editions, a smaller version, "Discovering the Essential Universe," and a version with a different order of material, "Discovering the Universe: From the Stars to the Planets."

Based on my teaching throughout the 1980s and 1990s, I became acutely aware that the hundreds of thousands of students taking astronomy courses around the world have many preconceived notions about nature that are incorrect, making it difficult for them to understand and believe the correct science. I set about identifying these misconceptions, learning where they came from, finding ways to undo them, and sharing that knowledge. This led to my book "Heavenly Errors" (2001: Columbia University Press) and a web site that lists over 1700 common, incorrect astronomical beliefs http://www.physics.umaine.edu/ncomins/ .

My book "The Hazards of Space Travel:A Tourist's Guide" (2007: Villard Press) evolved from an idea of friend and former editor Cliff Mills. Cliff wanted a book on natural disasters in space. I transformed the idea to disasters befalling humans in space. The idea is to give perspective space travelers a "heads up" as to what they will experience off earth. While it is a tribute to NASA and the other space agencies around the world as to how few people have died or been injured in space, they nevertheless were not enthralled with a book that lays out the challenges faced in space. Perhaps I should have called it, "Packing for the Moon." Then it would probably still be in print.

On other matters, my younger son, Josh, is developing into a serious singer. He has a basso profundo voice and had his first solo back in 2011. He is the first soloist in this piece, but I recommend that if you listen to it, have your bass speaker cranked way up. http://www.youtube.com/watch?v=6kxYxZI1_lE

I am privileged to attend Renaissance Weekend activities. I also give talks around the world. Normally my wife, Sue, doesn't go, but in 2010, I was invited to give a talk at a Festival of Ideas in Edmonton, Alberta to discuss the question, "Are we alone in the universe?" with the Vatican astronomer Father Jose Funes. When Sue saw the list of other participants, she insisted on going. That was the first time she ever saw me give a presentation to the public. Father Jose and I presented in the center of a planetarium, with the projector lowered into the floor. We walked in circles on the improvised stage while we talked, so everyone could see us. Talk about theater in the round.