Is a planet able to sustain life without a moon? What are the major effects of a natural satellite on a planet and its fauna and flora ?

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    $\begingroup$ You have a lot of questions here, and right now as it stands, I think your question is too broad. There's also the issue of your title not really matching what you seem to be asking. You appear to want to know what would happen if Earth's moon disappeared, not if life could develop on a planet without a lunar body. I's suggest trying to figure out what it is you want to know the most, and break that into a single question we can give you an objective answer on. $\endgroup$ – Pleiades Jan 20 '18 at 17:32
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    $\begingroup$ Here is a place where you can post a rough draft of your question and get feedback: worldbuilding.meta.stackexchange.com/questions/4835/… and Here is where we have a short how-to on writing questions for the main site: worldbuilding.meta.stackexchange.com/questions/4877/… $\endgroup$ – Pleiades Jan 20 '18 at 17:33
  • $\begingroup$ Ok ok, I'll modify the question to make it narrower. $\endgroup$ – Yves LaFayette Jan 20 '18 at 17:52
  • $\begingroup$ I'd only ask one of your two questions. $\endgroup$ – Bellerophon Jan 20 '18 at 18:05
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    $\begingroup$ I voted to leave your question open, but it is still too broad. Life can exist without a moon. A large moon (like Earth's) primary effect is tides. But, tides effect the weather, ocean currents, coastal errosion, river deltas, and a whole lot more. We'd need to write a book to explain all the whats and hows. Why are you asking this question? What are you looking for in an answer? If we knew that, we could narrow our responses to be more productive for you. $\endgroup$ – JBH Jan 20 '18 at 18:14

Yes. There is no reason why a moon would be essential for life. Animals on Earth have adapted to the cycles of the moon. However, this would not be necessary on a planet without a moon.

Tides would probably be greatly affected without a moon. The sun would continue to exert force on the tides, but without a moon the tides would be much less extreme than they are today.

Nocturnal plants and animals would also be affected. Plants would not longer be able to do photosynthesis under moonlight. And animals that rely on the moonlight to hunt would no longer be able to do so. You might see more animals using echolocation like bats or heat sensing organs like pit vipers.

The moon also slows down earths rotation. Without a moon, earth would rotate a lot faster, which means the days and nights would be shorter. Plants and animals would therefore, have to adapt to shorter days and nights.

The greatest impact would be on earths axial tilt. The moon stabilizes earth's axial tilt, and without it, Earth's axis would wobble. This could have serious impact on earth's climate over time. However, it wouldn't prevent life from forming, as the tilt would only change over hundreds of thousands of years.



Can a planet without one or more moons be habitable?





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  • $\begingroup$ That's what I was looking for. I'm sorry if my question(s) were too ambiguous for some other gentlemen, but you have answered as I thought one would answer. Many thanks! You'll be the my guest in this world of mine without a moon, after I create and name it :D $\endgroup$ – Yves LaFayette Jan 20 '18 at 20:21
  • $\begingroup$ This article references a study that concluded larger outer planets, or retrograde spin, are just as good for long-term stability. $\endgroup$ – rek Jan 21 '18 at 3:00
  • $\begingroup$ For an example, early Mars would almost certainly have been habitable - that's why NASA has rovers there looking for conditions that would have supported life. While it does have moons, they're really small (and possibly captured asteroids, so they may not have been around then). Also note that Mars' rotation period is quite close to Earth's. $\endgroup$ – jamesqf Jan 21 '18 at 3:54
  • $\begingroup$ The effects of missing tides are discussed briefly in the Fleet Of Worlds trilogy by Larry Niven. Most shallow water sea life would die. $\endgroup$ – geon Jan 22 '18 at 12:59
  • $\begingroup$ @geon thank you. didn't think of that. $\endgroup$ – IEW Jan 24 '18 at 0:03

A planet would be able to sustain life, but chances of it evolving life would be smaller. How much smaller, nobody can say with any certainty.

  • a moon, especially a large moon, will result in a thinner, more fractured crust of its primary; this will significantly increase the radioactive background and possibly increase the rate of mutations that powers evolution. This theory was first advanced in the '60s and later found its way in Isaac Asimov's enlarged Foundation cycle (Robots and Empire) - it is indeed a key plot point since it is what enables Levular Mandamus' ploy to make Earth uninhabitable.

  • it is largely believed that life will originate in warm, shallow seas, and later colonize the land. This step will be greatly accelerated by the existence of so-called undertidal or intertidal environments, where conditions rapidly shift from marine to land. The first adaptations allowing organisms to survive a brief transition to a dry environment lead the way to organisms more and more adapted to air.

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