Friday, August 12, 2005

ENV: Today!

Annual celestial event returns
Perseid meteor shower to peak August 12
By Wil Milan,
SPACE.com

(SPACE.com) -- Every August, when many people go vacationing in the country where skies are dark, the best-known meteor shower makes its appearance -- the Perseids.

In 2005, the Perseids are expected to reach their maximum on August 12. Peak activity is unfortunately predicted for the daylight hours across North America.

Sky watchers are thus encouraged to watch during the predawn hours of Friday, August 12 and again during the early morning hours of Saturday.

Observers will be favored by an absence of bright moonlight during these intervals. At midnorthern latitudes, moonset occurs on the evening of August 11 at around 11-p.m. local daylight time and around 11:20 p.m. the following night.

Since dawn doesn't break until around 4:30 a.m., that means there will be about 5 to 5 1/2 hours of dark, moonless skies for the two best viewing nights for the Perseids.

Take full advantage of this year's favorable lunar circumstances. Next year, a bright waning gibbous moon will flood the after-midnight sky with its light and seriously hinder the Perseids.

Bits of a comet
We know today that these meteors are actually the dross of the Swift-Tuttle comet.

Discovered back in 1862, this comet takes approximately 130 years to circle the sun. And in much the same way that the Tempel-Tuttle comet leaves a trail of debris along its orbit to produce the Leonid Meteors of November, comet Swift-Tuttle produces a similar debris trail along its orbit to cause the Perseids.

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