A Special Full Moon

By , March 19, 2011

Tonight’s full moon, the Algonquin and backwoods “Worm Moon,” will be a bit special. The moon will be at lunar perigee, the closest it’s come to the earth in the past 18 years (so, the closest it’s been in Aly’s lifetime). That will be 221,567 miles (356,577 kilometers) away. Hopefully it’ll be clear enough here, near Haines, to see it. From the weather report, that looks very likely.

Worm Moon is the theme and title of today’s Mary Oliver poem for those readers who are reading her book, Twelve Moons, as a lunar calendar with me.

The Worm Moon would be the one in which the earth worms begin to become active enough to be noticed. Spring has sprung, the grass is riz, etc. We’re definitely ready for it. Spring is upon us, it’s time to move!

Remember, I’m not an astronomer, so I may have my terms incorrect here. I’ve read that this close proximity is called the moon’s “perigee,” but I also note that the moon reaches perigee once a month. This “super moon” proximity apparently happens at perigee, but that term may not fully describe this once-in-18-years closeness. At perigee, the moon will also be traveling at its fastest, 2,429 miles per hour. Apparently, we won’t notice much of a difference from earth; it’ll continue at an apparent speed of 1 moon width per hour. This will, however, make the phases around the full moon seem to change more quickly.

The moon appears 14% larger at perigee than it does at its most distant (apogee). That would mean that it’ll appear 7% larger than “normal” tonight. It’ll also be 30% brighter.

One of the theoretical functions of Stonehenge included tracking this 18 year cycle. It may have been used to predict the upcoming perigees for some unknown reason.

Apparently, some are predicting increased earthquakes during the full moon, arguing that the moon’s proximity will cause higher tides. The sea tides are always larger just after full and new moons (not on them, there’s a sort of momentum lag). We know that the next lowest low tide will be a -3.8 foot on our beach on March 21. We know this because we have a “date” to beach comb that morning. But, we have lower tides than that each year, lunar perigee or no. So, there seems to be little call for panic. Besides, perigee occurs every 18 years, so you’d think, if it actually caused these problems, we’d be well aware of that phenomenon by now.

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