Why We Need a Big Moon
Our Moon is very large compared to the moons of other planets in our solar system. The Moon is fully one-fourth the size of Earth, giving one of the largest Moon/Earth ratios in the solar system.
Other planets, Mars for example, have very tiny moons. Phobos and Deimos are essentially a couple of small potatoes orbiting Mars.
Jupiter and Saturn have large moons, but compared to the size of those planets, they don’t affect the planets they orbit that much.
Having such a large moon turns out to be a very good thing, especially when a planet is trying to harbor life. If there’s one thing life doesn’t need is huge chaotic changes to its planet’s orbital mechanics.
Because of our Moon, we have a stable inclination for Earth’s rotation axis (this is the axis around which the Earth spins once every 24 hours). It wobbles a bit, but nowhere near what it would if the Moon weren’t there to stabilize things.
If the Moon weren’t there, then the Earth’s rotation axis would chaotically change every few million years or so because of the gravitational pull from Jupiter and the other planets.
This tilt angle is very important to life because it causes the seasons. We are tilted a gentle 23 degrees relative to the Sun and this prevents wild angles of the Sun’s radiation on certain parts of the planet.
As it stands now, the extreme effects of this tilt are at the poles. With our current angle, Antarctica and the Arctic Circle are in darkness only a short time of the year.
Imagine if our tilt was 90 degrees, like it is on Uranus. Some parts of the planet would never see daylight and the winters and summers would be extreme on certain locations of the globe.
Life would probably thrive very well in certain spots, but without the Moon, that wouldn’t last. As soon as life got comfortable with that planetary configuration, BAM, another shift in the rotation axis would cause everything to either adapt fast or die.
Having a large moon insulates us from these large changes and dampens the effects of the gravitational tidal forces from the rest of the solar system.
Life would literally be a bitch without the Moon.
Moon Image Credit: Almighty Photography
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3 opinions for Why We Need a Big Moon
Samuel Forbes
Oct 31, 2007 at 1:17 pm
Very interesting article. Just another question. I hear the moon is slowly getting further away from the earth. What effect with this have on the earth long term?
Leon
Nov 30, 2007 at 4:27 pm
Wait…not to get too technical here, but life wouldn’t *literally* be a bitch without the Moon. Dogs would surely be under just as much evolutionary pressure as any other life form, and would have an approx. equal chance of dying out vs. adapting.
r06u3AP
Dec 9, 2007 at 9:27 pm
You know what I find interesting about the Moon also? That it’s apparent size as seen from the surface of the Earth is almost exactly that of the Sun.
If you don’t think that’s pretty darned weird, you haven’t thought about it.
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