Got a calendar? Circle this date: Sunday,
August 12th. Next to the circle write "
all night"
and "
Meteors!" Attach the above to your
refrigerator in plain view so you won't miss the 2007 Perseid
meteor shower.
"It's
going to be a great show, " says Bill Cooke of NASA's
Meteoroid Environment Office at the Marshall Space Flight
Center. "The Moon is new on August 12th--which means
no moonlight, dark skies and plenty of meteors." How
many? Cooke estimates one or two Perseids per minute at the
shower's peak.
Above:
A Perseid fireball photographed August 12, 2006, by Pierre
Martin of Arnprior, Ontario, Canada. [Larger
image]
The
source of the shower is Comet Swift-Tuttle. Although the comet
is nowhere near Earth, the comet's tail does intersect Earth's
orbit. We glide through it every year in August. Tiny bits
of comet dust hit Earth's atmosphere traveling 132, 000 mph.
At that speed, even a smidgen of dust makes a vivid streak
of light--a meteor--when it disintegrates. Because Swift-Tuttle's
meteors fly out of the constellation Perseus, they are called
"Perseids."
Note:
In the narrative that follows, all times are local. For instance,
9:00 pm means 9:00 pm in your time zone, where you live.
The
show begins between 9:00 and 10:00 pm on Sunday, August 12th,
when Perseus rises in the northeast. This is the time to look
for Perseid Earthgrazers--meteors that approach from the horizon
and skim the atmosphere overhead like a stone skipping the
surface of a pond.
"Earthgrazers
are long, slow and colorful; they are among the most beautiful
of meteors, " says Cooke. He cautions that an hour of
watching may net only a few of these--"at most"--but
seeing even one makes the long night worthwhile.
As
the night unfolds, Perseus climbs higher and the meteor rate
will increase many-fold. "By 2 am on Monday morning,
August 13th, dozens of Perseids may be flitting across the
sky every hour." The crescendo comes before dawn when
rates could exceed a meteor a minute.
For
maximum effect, Cooke advises, "get away from city lights."
The brightest Perseids can be seen from cities, he
allows, but the greater flurry of faint, delicate meteors
is visible only from the countryside. Scouts, this is a good
time to go camping.
Above:
The eastern sky, viewed during the hours before sunrise on
Monday, Aug. 13, 2007.
And
there's a bonus: Mars. In the constellation Taurus, just below
Perseus, Mars shines like a bright red star. Many of the Perseids
you see on August 12th and 13th will flit right past it. Instead
of following the meteor, you may find you have a hard time
taking your eyes off Mars. There's something bewitching about
it, maybe the red color or perhaps the fact that it doesn't
twinkle like a true star. You stare at Mars and it stares
right back.
Earth
and Mars are converging for a close encounter in December
2007. NASA is taking advantage by launching a new mission
to Mars--the
Phoenix Lander. Phoenix will touch down on an arctic plain
where it can dig into the ground and investigate layers of
soil and ice, searching for, among other things, a habitable
zone for primitive microbes. The launch window opens on August
3rd, so by the time the Perseids arrive Phoenix may be hurtling
toward the Red Planet. Landing: late Spring 2008.
It's
something to think about at four in the morning, with Mars
rising in the east, meteors flitting across the sky, and a
summer breeze rustling the legs of your pajamas.
Maybe
you should go circle your calendar again.
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