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What If the Earth Had Two Moons?: And Nine Other Thought-Provoking Speculations on the Solar System de [Comins, Neil F.]
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Longitud: 316 páginas Word Wise: Activado Idioma: Inglés

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Descripción del producto


"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"

Descripción del producto

"What if?" questions stimulate people to think in new ways, to refresh old ideas, and to make new discoveries. In What If the Earth Had Two Moons, Neil Comins leads us on a fascinating ten-world journey as we explore what our planet would be like under alternative astronomical conditions. In each case, the Earth would be different, often in surprising ways.

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 that won't last forever. Eventually the moons collide, with one extra-massive moon emerging after a period during which Earth sports a Saturn-like ring.

This and nine and other speculative essays provide us with insights into the Earth as it exists today, while shedding new light on the burgeoning search for life on planets orbiting other stars.

Appealing to adult and young adult alike, this book is a fascinating journey through physics and astronomy, and follows on the author's previous bestseller, What if the Moon Didn't Exist?, with completely new scenarios backed by the latest astronomical research.

Detalles del producto

  • Formato: Versión Kindle
  • Tamaño del archivo: 1150 KB
  • Longitud de impresión: 316
  • Números de página - ISBN de origen: 0312598920
  • Editor: St. Martin's Press; Edición: Reprint (30 de marzo de 2010)
  • Vendido por: Amazon Media EU S.à r.l.
  • Idioma: Inglés
  • ASIN: B005E8AMBK
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Opiniones de clientes más útiles en (beta) 4.3 de un máximo de 5 estrellas 22 opiniones
5.0 de un máximo de 5 estrellas Do yourself a favor and read this book if you are interested in Earth Science 11 de octubre de 2016
Por Jack - Publicado en
Formato: Tapa dura Compra verificada
It was upon reading this book, that I felt that I understood what causes the tide on the side of the Earth opposite that of the moon. Until this time, I had been given the common answer, which is quite incorrect and was in truth not at all a satisfactory answer. This second tide, btw, is owing to the fact that the Earth and the Moon revolve around the common center of gravity, which is a point called the barycenter and which exists about 1,500 miles below the surface of the Earth and not at the center of the Earth. Thus there is a centrifugal force component on the opposite side of the Earth from the Moon which causes the second tide.

Comins does an excellent job in bringing all sorts of other things to light in an entertaining way. He creates little SF stories to illustrate these situations, which I found a delightful way to introduce various scenarios. You will understand the early Earth and the massive tides we once had, why the Moon is slowly moving away from the Earth in its orbit, why its rotation is locked with one face always oriented towards us, and a lot, lot more once you read this book.

All in all an excellent book. I have recommended it to many and have given it as a gift as well.
8 de 8 personas piensan que la opinión es útil
5.0 de un máximo de 5 estrellas Excellent! Illuminating! 15 de agosto de 2010
Por HardlyWarren - Publicado en
Formato: Tapa dura Compra verificada
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.
1 de 1 personas piensan que la opinión es útil
4.0 de un máximo de 5 estrellas Thought provoking 8 de enero de 2012
Por Amazon Customer - Publicado en
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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.
4.0 de un máximo de 5 estrellas Fun book, better in paper 26 de octubre de 2012
Por D. Thompson - Publicado en
Formato: Versión Kindle Compra verificada
This is a collection of ten what-if scenarios for alternate earths in various solar systems. It includes the title scenario of Earth having two moons, how we would have gotten them, their effects on the Earth over time, and ultimately what's going to happen to them. Other scenarios include the Earth as a moon, the Moon in a retrograde orbit, other planets in Earth's orbit, Earth's elsewhere in time, Earth's elsewhere in the galaxy, and even what will happen to the Earth when the Milky Way and Andromeda galaxies eventually collide.

The nice thing about this for me is that he explores the science behind a variety of fantastical other Earths. In other words, he's done much of the homework for exotic SF locales. Most of the science is well-written and aimed at the educated layman. A few bits got boring for me, but by and large it was good stuff.

However, this was not a particularly good Kindle edition. The text and diagrams themselves were decent, but the final 15% was taken up by a useless index (i.e. it had no links back into the text) and a collection of footnote/endnotes with no context back to the earlier text. Some of this may be simple limitations of the format, but I would have liked to have seen them handle it differently. If the index was going to be that useless, it should have been removed, and if there was no way to handle the footnotes more elegantly, they should have been inlined parenthetically in the text.

So, I enjoyed the book immensely, but I wish I had bought the dead-tree edition instead.
5.0 de un máximo de 5 estrellas A great resource for wanna-be scifi writers 3 de febrero de 2014
Por Arturo - Publicado en
Formato: Versión Kindle Compra verificada
I downloaded this book looking for the information of the second chapter about how Earth would be if it were the moon of a larger planet. And not only did this book solved my questions entirely, I also learned tons of valuable information for the rest of the world-building I'm currently working on.
This book is great for anyone interested in the basics for planetary motion, stellar evolution, and the overall considerations which make life on our solar system possible. Comins explains wonderfully, he thinks like a scifi writer and delivers the kind of information and consequence-chains that you specifically search for.
A great read done by a great author
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