Full Moon effect debunked again

By Phil Plait | July 31, 2007 4:08 pm

An article just came out over the wire discussing a study which shows — yet again — that the phase of the Moon has no effect on humanly efforts.

Nurses, cops, doctors — they all swear that things get crazy around a full Moon. However, study after study shows that is simply not the case… yet the swearing continues.

I was interviewed this morning by Bill Kole, the reporter who wrote that article, but he didn’t use what I wrote. Oh well. Update: Well, this online version does have me quoted in it! Weird.
Just for grins, though, here is what I wrote him:

Never underestimate the power of anecdote! People read about this idea, and it makes some sort of sense — we’re raised with stories of werewolves, and the power of the full Moon on romance — and they believe it. After all, nurses, police, doctors, they can’t all be wrong, can they? Of course they can. Like anyone else, they remember the time the emergency room was a madhouse during a full Moon, and forget the dozens of times it wasn’t, or the far more common times it was crazy but there *wasn’t* a full Moon. That’s human nature.

The Moon does have a profound affect on Earth; it powers our tides, changes the Earth’s spin, and provides light at night (many animals have cycles based on the Moon), but there are no physical effects on humans themselves. The tides from the Moon are far, *far* too weak to affect us physically, and the gravity from it is incredibly weak as well.

Also, the gravity of the Moon does not depend on its phase at all; the orbit of the Moon is elliptical, so sometimes it’s closer, and its gravity stronger, than other times. But that’s different from its phase, which only depends on the geometry of the Earth, Moon, and Sun.

The tides we feel on Earth are greatest at full and new Moon, because the Moon and Sun align in the sky, and their tidal force combines. But again, that’s far too weak to affect humans directly… and if it did, we’d expect to see the same craziness at new Moon as we do when it’s full. We don’t.

Next time I’ll talk about sex instead of romance. That’ll up the chances of me getting in.


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