Friday, August 9, 2013

"Perseid meteor shower peaking Sunday and Monday nights"

From the San Jose Mercury News (my bold):
Dim the lights, grab a blanket and hope for clear skies -- an annual magic show, the Perseid meteor shower, can be seen Sunday and Monday nights [August 11/12 and 12/13].

You don't need tickets to view nature's free show. And no binoculars are needed, because the flashes may be anywhere in the sky though they will seem to come from the northeast.

"The crucial issue is that meteors are faint, so you need a location where the sky is dark," according to Andrew Fraknoi, chairman of the astronomy department at Foothill College in Los Altos Hills. "The darker your site, the more you will see."

Your best views come after midnight -- so it is an event most appreciated by night owls. That's because the Earth turns after midnight to face the shower, so the meteors come more directly at us. And the crescent moon has set, immersing us in darkness.

At its peak, it is possible to see up to sixty shooting stars per hour. The shower actually started in July and will extend for most of August, but with less drama.

The stars are called the sons of Perseus, because they seem to shoot from that constellation, named after the Greek demi-god famed for saving Andromeda from a sea monster. They were first recorded 2,000 years ago.

But they're not really stars -- just meteoric dust, no bigger than the size of a dime. They burn as they careen into the Earth's atmosphere at 7 to 44 miles per second.

"They are cosmic 'garbage' left over from a regularly returning comet, called Swift-Tuttle," after its discoverers, Fraknoi said. Leftovers from the early days of our solar system, the flashes are the last gasp of cosmic material that formed about 5 billion years ago.

To enjoy the event, get away from city lights and coastal fog. State or city parks or other safe, dark sites are your best bet. Dress warmly for night-time temperatures.

Once you have settled at your observing spot, lie back so the horizon appears at the edge of your peripheral vision, with the stars and sky filling your field of view. Meteors will grab your attention as they streak by.

Be patient -- because they are more subtle than fireworks, it may take up to 15 minutes for your eyes to adjust to the dark. Several minutes might pass without a single flash.

If it's cloudy, don't despair: another meteor shower, the Leonids, will spark the nigh sky on Nov. 16.

More about the Perseids at
From mid-northern latitudes, the constellation Perseus,
the stars Capella and Aldebaran, and the Pleiades
cluster light up the northeast sky in the wee hours
after midnight on August nights.
When is the best time to view the Perseid meteor shower? Don’t wait until the peak nights to watch for the Perseid meteors. You can start watching a week or more before the peak nights of August 11-12 and 12-13, assuming you have a dark sky. The Perseid shower is known to rise gradually to a peak, then fall off rapidly afterwards. So as the nights pass in the week before the shower, the meteors will increase in number.

As a general rule, the Perseid meteors tend to be few and far between at nightfall and early evening. Yet, if fortune smiles upon you, you could catch an earthgrazer – a looooong, slow, colorful meteor traveling horizontally across the evening sky. Earthgrazer meteors are rare but most exciting and memorable, if you happen to spot one. Perseid earthgrazers can only appear at early to mid-evening, when the radiant point of the shower is close to the horizon.

As evening deepens into late night, and the meteor shower radiant climbs higher in the sky, more and more Perseid meteors streak the nighttime. The meteors don’t really start to pick up steam until after midnight, and usually don’t bombard the sky most abundantly until the wee hours before dawn. You may see 50 or so meteors per hour in a dark sky.

How to watch the Perseid meteor shower. You need no special equipment to enjoy this nighttime spectacle. You don’t even have to know the constellations. But you’ll definitely want to find a dark, open sky to fully enjoy the show. It also helps to be a night owl. Give yourself at least an hour of observing time, for these meteors in meteor showers come in spurts and are interspersed with lulls.

An open sky is essential because these meteors fly across the sky in many different directions and in front of numerous constellations. If you trace the paths of the Perseid meteors backward, you’d find they come from a point in front of the constellation Perseus. But once again, you don’t need to know Perseus or any other constellation to watch this or any meteor shower.

Enjoy the comfort of a reclining lawn chair and look upward in a dark sky, far away from pesky artificial lights. Remember, your eyes can take as long as twenty minutes to truly adapt to the darkness of night. So don’t rush the process. All good things come to those who wait.

Meteor seen at Acadia National Park during the 2012 Perseid meteor shower. Photo from EarthSky Facebook friend Jack Fusco Photography. See more from Jack here.

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