My, What a Big Moon You Have!

In two days the moon will be full, and this will be one for the books.  Anyone observing the full moon this month might notice that she's bigger and brighter than usual.  The phenomenon will be interesting to observe, and the degree of fullness we'll see hasn't occurred for about twenty years, so it's worth stepping outside this Friday evening and gazing skyward.

The term for what we'll observe is a Supermoon.  Yes, really.  Supermoons occur when the moon enters 90% of its perigee at the same time it is full.  "Perigee" is a Greek compound that means "close to earth."  The moon's orbit around earth is not spherical, but elliptical, so the moon is not always the same distance from the earth.  The moon's perigee, then, is the section of its path that brings it closest to our planet.  So, that the moon would appear larger this month is logical.  But there's nothing like a fancy-schmancy lunar event to get people talking, and some interesting theories are out about what mischief the Supermoon will whip up for the denizens of Earth.

Some have already suggested that the Supermoon is to blame for the recent tectonic events in Japan.  Scientists quickly whisked away this theory for several reasons.  It's known that Supermoons, when full, increase high tides a little beyond their normal degree of fullness; this is called a proxigean spring tide.  But this increase is not enough to cause catastrophic events, and doesn't even occur until the moon is full, scientists say.

Still, there have been whisperings of earthquakes and volcanic eruptions.  Bloggers in China point to the cyclone that ripped through Darwin, Australia in 1974, and the tsunami that slammed into Indonesia in 2005.  Both preceded by Supermoons.  Australia's own astronomer Dave Reneke has gone on record saying, "Phooey."

A staff writer for Space.com holds astrologer Richard Nolle responsible for the Supermoon-Japan association.  Nolle takes credit (among other things) for both coining the term "SuperMoon," and foreseeing a disastrous weather event associated with the August 2005 Supermoon.  That event is better known as Hurricane Katrina.

The best balm for these concerns is knowing that Supermoons, despite the buzz and cool, capitalized "super" appellation (because there's no actual scientific term for the event, and full-moon-at-90%-or-greater-perigee lacks pizzazz), are actually pretty common.  Do the research yourself, at the next Saturn hour.  Find a moderate-to-sophisticated moon phase table and look up how many times the moon has been full at 90+% perigee; try to find weather events associated with these occurrences.  Take it a step further: research and compare the number of natural disasters in recorded history that occurred at times when the moon was not full at its closest approach to earth.  You may, or may not, be comforted by the results.

Whatever you believe about the associations between Supermoons and weather phenomena, it's plain to see that the moon holds many of us fascinated, scientists, astrologers, and lay-terrestrials alike.  If the skies above your home are clear this Friday evening, and the moon is visible, step outside and say hello.  Just don't tell her that she's looking bigger than usual.  She is a lady, after all.