What If Earth Had Two Moons
And Nine Other Thought Provoking Speculations on the Solar System
Author: Neil F. Comins
Publisher: St. Martin’s Press
Publishing Date: 2010
Pgs: 288
Dewey: 525 COM
Disposition: Irving Public Library - South Campus - Irving, TX
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REVIEW MAY CONTAIN SPOILERS

Summary:
“What if?” Science. The title questions and nine other scenarios about what Earth could be and what life, the past and the future would be like “If”.

Ten speculative essays with insights into Earth as she exists today and as she could exist tomorrow and the wheres, whys, and hows of other Earths that could exist and may exist out there around other stars.
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Genre:
Science
Space
Astonomy
Astrophysics

Why this book:
Always fascinated by space and what ifs.
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Favorite Concept:
This has a little bit of everything in it; how planetesimals react in a ring system, why galaxies further away seem younger, though they're not, the evolution of stars and spiral galaxies, etc etc. All kinds of lay astronomy and galactic cosmology.

So, Mizar and Alcor are both double stars. And Mizar, itself, is a pair of double stars. So, it is a six star system. One more star and that would be Isaac Asimov's Nightfall planet.

Hmm Moments:
Makes sense that the capture of the second moon almost destroys Dimaan, Earth in this context.

The idea of Earth as a moon of a gas giant was fascinating.

WTF Moments:
Horror of being Galileo was not what I expected to find in the opening pages of this book.

Meh / PFFT Moments:
Since all of these What-Ifs center on Earth, calling all of the planets in question by different names is a bit silly.

Wisdom:
Looking at all these scenarios and the potentialities, we’re probably really lucky that we only have one moon.

The question is easy to answer. The reason why we haven't had an interstellar visitor upset the solar system, the sun, or the planets, in the 4 and 1/2 billion years, is because space is big and there is a lot of empty space in it.

Juxtaposition:
In Nocturnal Hunter intelligent evolution, instead of an Arboreal Progenitor intelligence, on a two-moon planet, the dominant species would probably be feline or chiropteras instead of primates...or whatever the alien physiology version would be

So, the two moon system could become one after collisions and amalgamation leaving one large Moon. Possible. Equally, and I would say more likely, actually, space is big and empty. The two moons could miss each other for eons and epochs and possibly never, ever, collide. I submit that that's more likely.

The Unexpected:
Wasn't expecting the fictional accounts incorporated into this book.

So a moon orbiting retrograde is in a death spiral, interesting. Does that apply to all the retrograde moons orbiting the gas and ice giants in the outer solar system.

All these, various, what-if scenarios involving the Earth-Moon system are teaching me orbital mechanics without the math, excellent.

Missed Opportunity:
The Earth as the moon of a gas giant gives me a real Pitch Black feel. Doesn’t touch on what would happen to the planet and the life on it when the long term conjunctional eclipse happens as it no doubt would. Because, even if the moon-earth is tidally locked to always show the same face to the planet below, the gas giant would not suffer under the same limitation. Eventually, the moon-earth would fall into the long deep shadow and if that eclipse were longer than a day or two, things would get hairy for life on the surface of the moon-earth.
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Last Page Sound:
Interesting questions, interesting answers. I'm glad the author used science to answer these thought experiments.
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2.5 stars.

Parts of it were interesting, but nothing is really gained by reading the introductory vignettes. Unlike others, I won't criticize the renaming of the different scenario planets because of the way the names were subsequently used in the discussion. Thanks to the unknown library patron who pointed out the mistakes in the text which I had glossed over. Actually, some of the information was dated, even for 2010. Perhaps it's a consequence of the chapters having been written separately.

However, the almost exclusive use of Imperial units throughout is inexcusable. Talking about a scale of 10^-13 inches is nonsense. Talking about the temperature of stars in Fahrenheit is just...ugh (I don't care if he quotes them Kelvin too). The author even brought up slugs! [A slug is an American Imperial unit of mass.] ( )

Very helpful as I was just making stuff up for ' Verthandi '. Answered some questions. ( )

Very helpful as I was just making stuff up for ' Verthandi '. Answered some questions. ( )

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. ( )