It’s all the Moon’s fault — or is it?
With a “supermoon” lunar eclipse occurring at the end of the month, you can count on all kinds of Moon coverage in the popular press. And one particular piece of conventional wisdom about the full Moon is sure to surface more than once. Ask a city fire fighter. Ask a nurse or crisis line operator. Ask the police. They’ll probably tell you that they always know when there’s a full Moon because things get a lot busier and more intense than normal. But is the Moon really at fault? And if it is, how does it do this?
If, as the many dedicated health and emergency providers (and astrologers) suggest, the Moon is a direct influence on our lives, for good or otherwise, what’s the mechanism? There are three possibilities: moonlight, gravity and tidal forces. Let’s take a look at how they might play a role in human affairs.
The Moon does not emit light — it reflects light from the Sun. But if that reflected sunlight is the source of the problem, it seems to me there’s an easy solution. Simply stay indoors and draw the curtains. Problem solved!
But what about that mysterious, unseen force called gravity? As Isaac Newton first explained, the gravitational attraction between any two bodies is determined by their combined mass and their distance from each other. That’s why the Sun exerts a much more powerful gravitational attraction than the Moon. If it were the other way around we’d likely orbit the Moon, not the Sun. In any case, the gravitational attraction between the Earth and Moon, rises and falls with the perigee/apogee cycle (the anomalistic month: 27.554 days), not the cycle of the phases (the synodic month: 29.530 days). So much for gravity.
That leaves tidal forces. Tides are related to gravity, of course. Tidal forces build up when one large body is close enough to another that the gravitational pull is stronger on one side of the body than on the other. Although the Moon is much less massive than the Sun, it’s 400 times closer, so its gravitational pull is strong enough to create stresses throughout our planet. Those stresses are mostly relieved by water in the oceans, which results in the tides we see worldwide. Some advocates of the full-Moon effect assert that because humans are largely composed of water, there are “lunar tides” rushing back and forward through our bodies causing “disturbances.” But, of course, the distance from the Moon to our heads, and from the Moon to our feet is, for all intents and purposes, the same. No tides, no tidal stress.
But if the Moon’s effects aren’t due to light, gravity or tides, what’s going on? Perhaps the Moon’s power is magical or supernatural? But if that’s the case, it’s beyond the ability of science to investigate.
It turns out that in fact, there’s no evidence to support the premise in the first place. I know this first hand. Back in 1991, there was an article by Greg Middleton in the Vancouver Province newspaper, in which Janet Calder, Great Vancouver’s 911 administrator, cited the full Moon for an increasing number of calls. When I read this I realized that her detailed statistics could be an invaluable tool in any investigation of the full-Moon effect. Ms. Calder kindly sent me her lists of calls received every day from July, 1990 to February, 1992. The number of calls handled per day was between 1,500 and 2,500. That’s certainly a statistically-valid sample. But when I looked at the stats carefully, I found there was no correlation whatsoever between the peaks and valleys in their records and the full Moon. There was no full-Moon effect.
As one who loves following the Moon on its journey through our sky and exploring the lunar surface with my telescope, I’ll always defend it against spurious claims. But perhaps doing so is the one real form of Moon induced madness!
David Rodger observes the Moon, planets and stars from his home in North Vancouver, BC. In 2016 he will celebrate 60 years as an astronomy and science writer.