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What if the moon didn't exist : voyages to…
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What if the moon didn't exist : voyages to earths that might have been (original 1993; edição 1993)

por Neil F. Comins

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1724157,448 (3.82)2
"Any discussion about finding life elsewhere in the universe always leads us to analyze the factors that make life possible on Earth. What would the earth and life on it be like if our planet had formed under different circumstances?" "What if the earth were less massive, or if the sun had ended up with more mass when the solar system was formed? What would happen if a star exploded near the earth, or passed through our solar system right now? What if a black hole passed through the earth? What if our ozone layer became depleted? What would happen to life on Earth?" "In this engaging and accessible exploratory work, accomplished astronomer Neil F. Comins shows how these and other hypothetical situations would affect our planet and the life it sustains, by extrapolating from our present condition and applying plausible astronomical and geological theories." "What if the moon didn't exist, for example? Well, Comins explains, the earth would rotate more than three times faster than it currently does, and our tides would be much lower. There would be recurrent gale-force winds like those on Jupiter, making it a challenge for "tall" beings (like humans) to evolve. And the atmosphere would have taken millions of years longer to convert from one dominated by carbon dioxide to the life-giving nitrogen/oxygen atmosphere of today (if it could at all - the atmosphere surrounding moonless Venus is still predominantly composed of carbon dioxide)." "By following up its initial imaginative leaps with careful analysis, What If the Moon Didn't Exist? offers the reader a fresh understanding of our place in the solar system, and a deep appreciation of how fragile a habitat the earth is."--BOOK JACKET.… (mais)
Membro:arianr
Título:What if the moon didn't exist : voyages to earths that might have been
Autores:Neil F. Comins
Informação:New York, NY: HarperCollins, c1993. xv, 315 p. ; 22 cm. 1st ed
Coleções:A sua biblioteca
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Etiquetas:space

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What if the Moon Didn't Exist? : Voyages to Earths That Might Have Been por Neil F. Comins (1993)

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Interesting idea, poorly executed. Author Neil Comins is an astronomy professor at the University of Maine. The premise of What If the Moon Didn’t Exist? is alternative solar system astronomy; Comins presents a series of scenarios for alternate Earths, giving each a cute little name: Solon, where the Moon never formed; Lunholm, where the Moon is much closer; Petiel, where the Earth has less mass; Urania, where the Earth’s axis is tilted 90° to the plane of the ecliptic like Uranus; Granstar, where the Sun is more massive; Antar, where a supernova goes off near the solar system; Cerberon, where another star passes through the solar system; Diablo, where a black hole passes through Earth; and two versions of Earth, one where our eyes are sensitive to other wavelengths and one where the ozone layer is depleted (the book dates from 1993, where ozone depletion rather than climate change was the man-made disaster du jour.)

The ideas are interesting enough; the main problem is there are no illustrations, no physics and mathematics to speak of, and Comins often strays outside of astronomy into biology and human behavior. The “no illustrations” problem comes to the fore when Comins discusses his hypothetical Urania; he has to explain seasonality on the extant Earth and seasonality on Urania solely with text, leading to extremely awkward constructions like asking the reader to imagine holding a pen over paper at a 23 ½° angle and then drawing circles while keeping the wrist stiff; his description of the seasons on the imaginary Urania has to go through even more convolutions.

Somewhat more unsettling, since Comins is an astronomer, is his explanation of oceans tides (which figure on the moonless Solon and the “supermoon” Lunholm). This is Comin’s explanation of why there are high tides on opposite sides of the Earth:

“The reason there is a second high tide on the opposite side of the Earth is the Moon pulls the bulk of the Earth away from the oceans on the far side.”

This is just plain wrong (or, at best, extremely misleading); the reason there are tides on opposite sides of the Earth is tides are raised by the horizontal component of solar and lunar gravitational attraction, not the vertical component. There’s a good explanation on the NOAA web site; see Section 4, “The Tractive Force”.

Comins gets into similar trouble when he strays into biology; in his chapter on the potential effects of a nearby supernova (his hypothetical one is 50 light years away) he devotes a couple of paragraphs to the mutations that will be caused by supernova gamma rays and X-rays, hypothesizing such things as mutant mice with poisonous fur, mutant wheat that poisons competing strains, and even mutant humans. This is the “mutation as magic” realm of comic book superheroes; in anything more complicated than bacteria, recombination is a – well, astronomically – more powerful force for genetic change than point mutations.

All that being said, some of the ideas presented are intriguing. I’d like to have a solar system simulation program that would allow me to try out some of the ideas; cursory googling doesn’t reveal anything that allows me to start out with the extant solar system and play around with solar evolution and planetary parameters, but I’m sure something will turn up. ( )
1 vote setnahkt | Jan 1, 2018 |
A fun series of essays that teaches a bit of astronomy and physics by hypothesizing different scenarios for the origin of the earth-moon system. ( )
  nillacat | Oct 22, 2007 |
I love this presentation of astronomical information. Changing variables helps me understand how something works. ( )
  neontapir | Oct 6, 2007 |
I feel that the author, an astronomer or astrophysicist, doesn't realize how flexible life is. Assuming that there is life, if the earth is warmer, we'd evolve proteins that could stand the heat. However, it's interesting as he goes through various scenarios about what the Earth would be like if the solar system were slightly different.

This is an interesting book but kind of wordy. I think that the author probably writes as he thinks, in well-connected but fairly convoluted sentences, and hasn't realized the need to smooth them out for readers. ( )
  monado | Jul 23, 2006 |
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Even as late as 1944, the Earth was assumed to be so massive and resilient that humans felt few qualms about dropping millions of pounds of bombs on it.
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"Any discussion about finding life elsewhere in the universe always leads us to analyze the factors that make life possible on Earth. What would the earth and life on it be like if our planet had formed under different circumstances?" "What if the earth were less massive, or if the sun had ended up with more mass when the solar system was formed? What would happen if a star exploded near the earth, or passed through our solar system right now? What if a black hole passed through the earth? What if our ozone layer became depleted? What would happen to life on Earth?" "In this engaging and accessible exploratory work, accomplished astronomer Neil F. Comins shows how these and other hypothetical situations would affect our planet and the life it sustains, by extrapolating from our present condition and applying plausible astronomical and geological theories." "What if the moon didn't exist, for example? Well, Comins explains, the earth would rotate more than three times faster than it currently does, and our tides would be much lower. There would be recurrent gale-force winds like those on Jupiter, making it a challenge for "tall" beings (like humans) to evolve. And the atmosphere would have taken millions of years longer to convert from one dominated by carbon dioxide to the life-giving nitrogen/oxygen atmosphere of today (if it could at all - the atmosphere surrounding moonless Venus is still predominantly composed of carbon dioxide)." "By following up its initial imaginative leaps with careful analysis, What If the Moon Didn't Exist? offers the reader a fresh understanding of our place in the solar system, and a deep appreciation of how fragile a habitat the earth is."--BOOK JACKET.

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