PLANETS ALIGN FOR
THE PERSEID METEOR SHOWER
by Dr. Tony Phillips
Reprinted from
science.nasa.gov
2010 August 5
You know it's a good night when a beautiful alignment of planets
is
the second best thing that's going to happen.
Thursday, August 12th, is such a night.
The show begins at sundown when Venus, Saturn, Mars and the
crescent
Moon pop out of the western twilight in tight conjunction. All
four
heavenly objects will fit within a circle about 10 degrees in
diameter, beaming together through the dusky colors of sunset. No
telescope is required to enjoy this naked-eye event:
The planets will hang together in the western sky until 10 pm or
so.
When they leave, following the sun below the horizon, you should
stay,
because that is when the Perseid meteor shower begins. From 10 pm
until dawn, meteors will flit across the starry sky in a display
that's even more exciting than a planetary get-together.
The Perseid meteor shower is caused by debris from Comet
Swift-Tuttle.
Every 133 years the huge comet swings through the inner solar
system
and leaves behind a trail of dust and gravel. When Earth passes
through the debris, specks of comet-stuff hit the atmosphere at
140,000 mph and disintegrate in flashes of light. These meteors
are
called Perseids because they fly out of the constellation Perseus.
Swift-Tuttle's debris zone is so wide, Earth spends weeks inside
it.
Indeed, we are in the outskirts now, and sky watchers are already
reporting a trickle of late-night Perseids. The trickle could turn
into a torrent between August 11th and 13th when Earth passes
through
the heart of the debris trail.
2010 is a good year for Perseids because the Moon won't be up
during
the midnight-to-dawn hours of greatest activity. Lunar glare can
wipe
out a good meteor shower, but that won't be the case this time.
As Perseus rises and the night deepens, meteor rates will
increase.
For sheer numbers, the best time to look is during the darkest
hours
before dawn on Friday morning, Aug. 13th, when most observers will
see
dozens of Perseids per hour.
For best results, get away from city lights. The darkness of the
countryside multiplies the visible meteor rate 3- to 10-fold. A
good
dark sky will even improve the planetary alignment, allowing faint
Mars
and Saturn to make their full contribution to the display. Many
families plan camping trips to coincide with the Perseids. The
Milky
Way arching over a mountain campground provides the perfect
backdrop
for a meteor shower.
Sky map of the event can be found here:
http://tinyurl.com/2d74crp