When moon comes over mountain, it’ll be big, beautiful

Published 5:54 pm Friday, September 21, 2007

It seems like there are zillions of songs about the moon and moonlight.

Of course there’s the old classic “Shine on Harvest Moon,” but there are also “Moon Over Miami,” “There’s a Moon Out Tonight,” “Moonlight Serenade,” “Fly Me to the Moon” and many more.

One of my personal favorite moon songs is the 1976 classic “Moonlight Feels Right” by the less-than-legendary group Starbuck.

If the weather cooperates this coming week, the moonlight will really feel right because a full harvest moon will be shining on us.

Yes, I know the full moon whitewashes out a lot of celestial treasures available through your telescope, but you have to be completely without feeling and emotion not to be drawn to that heavenly light. That’s especially true with the harvest moon.

Technically, the harvest moon is the closest full moon to the first day of fall, otherwise known as the autumnal equinox, and because that occurs this weekend, the full moon this week is a bonified full harvest moon.

The actual date of the full moon, when the Earth is exactly between the sun and the moon, is Wednesday but the moon will be full for all practical purposes most of this week.

What makes the full harvest moon so special is that because of the unique celestial mechanics this time of year, the moon rises only about 20 minutes later each evening, getting the moon up in the eastern sky close to sunset most of this week.

Normally, the full moon rises about 35 to 40 minutes later each night so most folks, especially those with early bedtimes, don’t enjoy as many consecutive evenings of full or near full moonlight.

The harvest moon got its name because of all the help it gave farmers in the days before electricity and headlights on tractors. Because moonlight was available so close to sunset night after night they could extend their time in the fields.

Sometimes, with the help of strong coffee, eagle eyes and a lot of determination they could pull all-nighters, pulling in the crops in dimly moonlit fields.

Even now with headlights on tractors the full harvest moon is still a friend to farmer.

The moon usually sports an orange hue when it rises, but the rising harvest moon hangs on to its color longer into the evening. That’s because the harvest moon rises at a lower-than-usual angle to the horizon, so the moon hangs lower in the sky longer.

Whenever you view astronomical objects close to the horizon, you’re looking through a lot more of Earth’s atmosphere. There’s a lot more dust and pollutants, natural and otherwise. That thicker atmosphere scatters away all but the reddish orange components of the moon’s light.

When the moon climbs higher and higher, you see it through less and less atmosphere and you can see the full spectrum of its light, which melts into the familiar white that we enjoy in the crisp autumnal air.

Another thing you’ll notice is that the moon appears gigantic when it first rises but shrinks after an hour or so. The moon seems bigger when it first rises because you’re comparing it with land objects — trees and strip malls.

You can prove this to yourself with a paper clip. When you first see the moon above the horizon, hold a paper clip at arm’s length and bend it apart so the moon fits exactly between the two ends. About two hours later take that same bent apart paper clip and once again hold it at arm’s length toward the seemingly smaller moon.

Guess what?

It will fill the space between the paper clip ends exactly as it did at moonrise.

Mike Lynch is an amateur astronomer and professional broadcast meteorologist for WCCO Radio in Minneapolis and author of the new book ‘Washington Starwatch,’ available at bookstores and on his Web site, www.lynchandthestars.com.