What if the Moon didn't exist?

The Life's Little Mysteries blog is in the midst of a string of posts that are, basically, like Marvel Comics "What If?" series as applied to the scientific history of Earth.

For example: What if humans had evolved to include more than two sexes, or to need three or more sex cells in order to procreate? What if Pangea (everybody's favorite supercontinent) had never split into chunks? What if Earth had never been in a massive collision with another, huge space object—meaning, what if the Moon didn't exist?

Now, if you've read very many of the comics you know that the answer to "What If?" is almost always "everybody dies". This series of posts is a bit less fatalistic. But, still, the point is made—these changes would radically alter life as we know it, and not necessarily in ways that sound like a lot of fun.

Take that question about the Moon. The implications of a Moon-less Earth are farther-reaching than you might guess:

Huge tides generated by the moon – which orbited much closer to Earth when it formed – washed the chemical building blocks for life from land into the oceans and helped "stir up the primordial soup," said Neil Comins, a professor of physics at the University of Maine.

The moon's gravity has helped slow Earth's rotation from an initial six-hour day to our current 24-hour day, while also stabilizing the tilt of our planet's axis, and thereby moderating the seasons. Life forms on a moonless Earth would therefore have different patterns of activity per the short days and nights, Comins told Life's Little Mysteries. These creatures might need to migrate more frequently to cope with extreme climate swings as well.

What If the Moon Never Formed?

Via "It's Okay to be Smart"


  1. Neil Comins actually wrote a whole book called “What if the Moon didn’t Exist? Voyages to Earths that Might Have Been” – I have a copy which I enjoyed immensely. Contrary the astronomical fine-tuning claims of some ID creationists, he makes a good argument that you can seriously mess with the planet without ruling out complex life. 

    Even so, I thought that he was a little pessimistic at times – for example, he suggests that a moonless world, lacking tidal mixing of the oceans’ chemicals, would have a delayed emergence of life. However, such a world would also have faster winds, leading to more erosion and wind-blown dust (which is important to ocean life even today) as well as stronger wind-driven ocean currents. Might these factors not counter-balance the reduced tidal mixing?

  2. If memory serves, a magazine article about twenty years ago said that without the Moon, the Earth’s magnetic field would be much weaker, a hundredth or even a thousandth of what it is with the Moon.  Is that statement accurate?

  3. The universe is they way that it is because if it weren’t, then we wouldn’t be here to observe it. So says the anthropic principle: http://en.wikipedia.org/wiki/Anthropic_principle

  4. Mars has a 24-hour day (approximately) with no large moon to explain it. Could it be that the same impact that formed the Moon also spun-up the Earth?

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