Stardate:08:05:98
Watch Out for Falling Rocks!
The Perseid meteor shower makes it's annual return
to Earth this month, certain to delight people worldwide once again. Beginning
sometime around August 10th, and ending about August 14, this dazzling
display of shooting stars will peak between the night of the 12th and just
before dawn the morning of the 13th. However, some shooting stars produced
by the Perseid group might be seen from the last week of July until the
third week of August.
The Perseid meteor shower is likely the most watched
meteor shower each year. This is not because it is the most spectacular
of the years annual meteor showers (being outdone by the Geminids), but
because it occurs during the warmest month of the year, when more people
are outdoors, staring up towards the sky. It is, however, the second most
spectacular meteor shower of the year most years, and is often quite a
sight.
The Moon will present some difficulty in viewing
the meteors this year, as it is gibbous (about 2/3 visible) on the night
of the 12th. However, it will not rise that night until 10:45, leaving
early evening observation unaffected.
At 10 p.m. on the night
of the 12th, the constellation Perseus (around which the shower is centered)
will barely be rising over the eastern horizon. The Moon will not have
risen yet, giving us a spectacular chance to watch the meteors seem to
steak in from over the horizon.
The very best viewing, however, will be just before
dawn on the morning of the 13th. At 5 a.m., nearly an hour before sunrise,
Perseus will be due east. The Moon, nearly 40 degrees away, should present
a minimal problem. Also, low towards the cast are the planets Venus and
Mars huddled close together. Less than four degrees away from the Moon
is the planet Saturn. Look 35 degrees to the west of the Moon, and you
will see the majesty of the planet Jupiter. This is also the exact time
that the Earth will be plunging head first into the thickest part of the
debris field.
Some interesting long exposure photographs may be taken by setting a 35mm
or larger camera on a tripod, and aiming towards the center of the shower.
Set the camera on the bulb, or "B" setting, and let the frame
expose for perhaps 5, 10, 15 or even 30 minutes. A film rated at 400 ASA
is often your best bet for such exposures.
The Perseid meteor shower is caused by the Earth
crashing into rubble left by the comet Swift-Tuttle. Leaving behind a trail
of dust and gravel each time it visits the neighborhood of the Sun, the
shooting stars we see are caused by the atmosphere quickly burning these
comet crumbs as they plunge to a fiery finish. The Perseids usually range
between 40 to 80 meteors per hour, or about one per minute.
They were first cataloged in a major paper by
Edward Herrick (1811-1862) in the year 1837. A failure at business, his
bookstore was near bankruptcy at the beginning of August, 1837. He went
out for a walk on the evening of the 9th, and noticed the large number
of meteors in the sky. He later collected data for the years 1834 to 1837,
and proposed that there was an annual meteor shower every August. He then
made several correct conclusions in later papers, including the realization
of the cause of these showers. He was later stripped of the honor of having
discovered the- Persceid meteor shower. However, Herrick was later given
an honory Master of Arts degree from Yale, which then built a new library,
and made Herrick the librarian. He wrote his own death notice a few days
before he died in 1862.
Once every three decades
or so, the Leonid meteor shower blazes forth with between hundreds and
thousands of meteors per hour. One of these impressive shows should occur
around the middle of November in either this year and/or next year. One
Boston bound astronomer described it's apperance over 150 years ago as
having "as many meteors as there are flakes in a snowstorm, and many
of those were as bright as full Moons". Until then, we'll just have
to settle for the beauty of the Perseids.
Clear skies, and good viewing.
Jim Maynard is the head of the astronomy department
at Earth Treasures and has been an amateur astronomer for more than 20
years. He is a physics student at Keene State College and leads star parties
at Wheelock Park in Keene, New Hampshire. If you have any questions about
astronomy or star gazing, call him at 603-352-7192.
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