WHAT'S UP: Great night to be outdoors

Aug 12, 2011


With the full moon to light the way, you can get outdoors in the middle of the night and explore. The full moon late at night provides a surprising amount of illumination — it shines back about 10 percent of the incident sunlight that shines on it. You can even see your shadow by the full moon.

Seeing stars on a full moon night can be disappointing. The light from the full moon brightens the sky so that only the brightest stars can be seen; especially near the moon in the sky.

This can work to your advantage, however, if you’re trying to pick out constellations.

When the sky isn’t completely dark, bright stars that form the familiar constellations stand out in better contrast than when the sky is completely dark and speckled by thousands of faint stars.

This evening, look for the constellation Lyra anchored by the bright star Vega high overhead around 10 p.m.

Slightly to the east, you can spy Cygnus the Swan. And to the north, of course, the Big and Little Dippers and Cassiopeia — which looks like a W, reminiscent of the big W in the 1963 film “It’s a Mad, Mad, Mad, Mad World.”

If you stay up really late, however, you can glimpse the future. The most impressive constellations of winter — Canis Major, Orion, Taurus the Bull and the Pleiades, and Perseus — rise in the east and climb to the south well after midnight.

The stars rise four minutes earlier each night, compared to the night before. This amounts to about 30 minutes earlier each passing week, and two hours earlier each month.

A constellation that rises at 3 a.m. in mid-August will rise at 9 p.m. in mid-November.

To top it off this evening, Earth is passing through the debris stream of a comet called Swift-Tuttle (Swift is a surname, not an adjective), as it does every year in mid-August.

What this means for us is meteors. Lots and lots of meteors.

The Perseid meteor shower — so named because shooting stars in this stream seem to emanate from a point in the constellation Perseus — is among the best of the year, producing as many as 100 or so meteors per hour. Although visually this year’s Perseid meteor shower will be somewhat diminished by the full moon, the brightest shooting stars will still be apparent.

And who knows? — a near direct hit by a meteor, like the one that rocked Ottawa County in the early evening on Nov. 26, 1919 (see Kevin Collier’s Aug. 8 “Strange Grand Haven” column, “1919 meteor strikes cause Ottawa county residents to flee homes”), cannot be ruled out.

See you out there.

— By Doug Furton, a member of the physics faculty at GVSU. Send questions and suggestions to dgf@inbox.com.


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