What if the Earth had no moon (part 2)

A while ago, in this blog post, I mused about what the earth would be like with no moon. You may hear the Moon blamed for things as diverse as reproductive cycles and people’s moods, but in that post, I argued that if all of a sudden, we’d find ourselves without a moon, not a great deal would change. The Sun causes tides, albeit smaller ones, and any stability issues of the Earth’s axis would not change overnight.

But this is not a realistic scenario. The Moon isn’t going to just disappear (the subject of Death Star-like blasting a planet apart is a subject for another blog post, but let’s just say it’s physically nigh impossible). The real question I should have asked is: what would life on Earth be like if Earth had never had a moon? If the Pluto-sized object that may or may not have collided with us to form the Earth and Moon as we know them had missed the Earth, and sailed straight on, to eventually burn up in the Sun.

The situation would look vastly different. The Earth-Moon system is vastly different from other known planets in terms of relative size. Only the largest moons of Saturn and Jupiter are similar in size to our Moon, but those planets are of course much more massive. The Earth-Moon system could well be referred to as a double planet. Of course Earth and Moon affect each other, and this influence comes in the form of gravity. While the gravity of the Moon affects all surfaces of the Earth equally, it’s only the oceans that can react to this gravity. Yeah, that’s how the tides are formed.

Imagine the Earth as an oblong bubble of water, with bulges both on the side where the Moon is at and the opposite side. This bulge orbits the Earth at the rate the Moon does. But the Earth itself rotates inside this envelope of water, and this creates friction at the place where water and solid surface meet. In effect, the water is forever trying to keep up with the planet. Friction creates warmth, and yes, loss of speed.

So it is that over the four-plus billion years of the Earth’s lifetime, the rotation speed of the Earth has slowed from an eight-hour day to our current twenty-four hours. Is still slowing, in fact.

Of course life on a planet with days of eight hours would be very different. We’d experience vastly more powerful weather and especially wind systems. With a rotation speed like that, there would probably not be much opportunity for much North-South weather movement, but we’d have strong bands of air movement, much like Jupiter (which has a daylength of ten hours). We’d have similar ever-lasting cyclonic systems.

And what would it do to the seashores, having the tides jump up twice in eight hours?

Or to the biology of animals evolving with that kind of daylength? Would we all have nervous tics from seeing the Sun whizz by?


11 comments on “What if the Earth had no moon (part 2)

  1. H’m, the link to your earlier blog post doesn’t seem to work.

    Anyway, I like this blog post, and I thought I’d mention that I heard on a Science Channel documentary that the Moon is moving away from the earth, but I think it’ll be a long, long time before we look up and it’s not there.

    • Thanks for letting me know. All fixed now. It seems the new version of Word (which I started using yesterday) has some weird quirks in relation to copying links that it didn’t tell me about.

      You’re also right about the Moon moving away. Earth also exerts gravity on the Moon, which results in it slowing down, and thus moving away.

    • Ironically, it’s the fact that Earth’s bulge of water from the tide is pushed forward a bit by the Earth’s rotation that actually exerts it’s own slight gravitational tug on the moon, speeding it up and hence transferring some angular momentum to it, causing its orbit to get bigger. The moon’s not going to fly off into space, though. It will stop moving further away when it and the Earth are both tidally locked, with the same side always facing the other (this is already true of the moon and Earth would eventually join it if it wasn’t going to be consumed by our dying sun first.)

  2. I read somewhere that moon dust is so fine it would stick to you…or anything for that matter…I could be wrong, but one would think any manned (future) base would need to take that into account. one can imagine air filters would get clogged very quickly. sort of like driving up north in western Australia when I lived there, the red dust was everywhere. imagine a whole landscape of dust with no vegetation. it would be a nightmare I would think

    • LOL Mark I was just thinking about you.

      Yes, there would be lots of dust on the Moon (and on Mars for that matter), worse than in WA. When we lived in Townsville, we bought a car at a government auction that had belonged to Queensland Rail in Mt Isa. Every time you hit a bump (or some corrugations) dust would come out of unimaginable places. Moon dust is worse not only because it’s finer (no wind to move it about) but it is also very abrasive because there is no erosion at the Moon. Because it is so dry there (through lack of atmosphere) everything on the Moon is going to be charged with static electricity. Worse also the Moon landscape has no colour, and neither does the sky.

  3. I hope your thoughts were good 🙂

    My car from up north used to do that, too. Red dust was even inside the dash board clock…I still don’t know how it got in there! LOL

    Yeah, I heard about the abrasive/static electricity and all the other things, too, about Moon dust. Well, it would be an inhospitable place to settle, wouldn’t it? Some challenges ahead for humanity, I think.

    • I was actually thinking I should have written up a review of that book of yours I read 😉

      I think the challenge of writing realistic SF is imagining those everyday situations and annoyances and making them real for your characters.

      • Was that the “Unicorn’s Peril” one I sent you?

        And yes, I agree 100% real life annoyances are what makes a situation believable when writing SF or Fantasy or any other speculative fiction. I like to imagine myself in a situation, say a spacesuit, and then go from there.

  4. Hello, Patty.

    I have heard the explanation for the tidal bulge on the far side of the world, but do not remember it. Could you remind me? Thanks.

    I have been following you on Twitter for a while — well, not that long, since I’m new there — but this is my first visit to your blog. I am very impressed, and am now following you here via Blogger.

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