Supermoon - Photo Credit: David Powell
TOKYO (majirox news) – Did Saturday’s “supermoon” cause Japan’s earthquake? In a panicky article, the Telegraph, a major English newspaper, asked astronomers and physicists this exact question. With true English reserve, instead of showing the reporter to the door, they politely answered the questions.
“I do hope I can mitigate panic and worry due to people blaming this earthquake on the so-called “supermoon,” wrote Astronomer Philip Plait on his blog, Bad Astronomy. “Despite what a lot of people are saying, there is no way this earthquake was caused by the moon.”
The moon sweeps around the earth in an elliptical orbit that runs in roughly 18-year cycles. Mankind has known this fact for the last 3,000 years or maybe more. Once in every 18 years or so, the perigee (closest point to the earth) of the elliptical orbit produces a supermoon because of its’ relative closeness to earth. Then it’s continuous shifting orbit takes it away again.
The last time the supermoon appeared was in 1993, and if one remembers, there was no catastrophic earthquake then. While science might take the romance out of things, it is marvelous for clearing the air.
This 18 year orbital cycle (there are several related cycles) was of great interest to the ancient Greeks and Babylonians. They used it to set their calendars and to predict eclipses. The different cycles are commonly used by astronomers to predict the moon’s orbit and the best known are the Metonic cycle, devised by Meton of Athens, who lived around 500 BC, and the Saros cycle, which was discovered by ancient Babylonian astronomers, but given its name by Edmund Halley.
By tracking these cycles astronomers predict eclipses and still use them to reset some calendars, such as the Islamic and Hebrew calendars, which are lunar, calculate the date of Easter, do flight planning for lunar probes and tidal analysis.
But earthquakes? Forget about it. If it was true, we would be having a major convulsion every 18 years, which isn’t true. And we have data stretching back to the time of the ancient Babylonians to back it up.
“The idea of the moon affecting us on Earth isn’t total nonsense,” wrote Plait, “But it cannot be behind this earthquake. In fact, the effect of the moon seems to be limited to the tides, and is not even responsible for any influence of the earth’s weather.
“Weather is caused by an incredibly complex interaction between the Earth’s rotation. Heat input from the Suns, the way the oceans absorb and radiate heat and a million other factors. If the moon continues in anyway, it is very, very small compared to these other massive factors”
For anyone who was lucky enough to see the supermoon in a location not obscured by clouds or the light pollution of a big city, you can be sure of seeing it again in 18 years, and it will be up there — big, bright and shiny, but not the slightest bit ominous.
Pierre Beaumarachais is a writer for Majirox News. pierre@majiroxnews.com
http://www.badastronomy.com/index.html
http://www.majiroxnews.com/2010/12/19/eclipse-of-the-moon/