by James L. (JimiJam)

The cosmos is filled with awe-inspiring spectacles on the most massive of scales: supernovas and nebulae, galactic collisions, radiant stars that easily dwarf our own, faraway planets only recently brought within reach of the astronomer’s sight.  For most of us, the opportunities to see such

(photo by Nick Ares)

wonders for ourselves are of course pitiably few; those of us who live in and around cities are accustomed not to a night sky full of fascinating displays unfold in slow motion, but rather the moon and only the brightest of stars, and glimpses of a few of our neighboring planets within the solar system.  So consistent are these extraterrestrial entities that we all too easily take them for granted.  Aside from the occasional lunar or solar eclipse, dazzling celestial events are, sadly, the exception, rather than the rule.  And yet, the universe has seen fit to grant us regularly scheduled viewings of one of the closest, most simple, and yet not so easily dismissed phenomena:  Meteors.

Approximately 1,000 tons of dust and rock enter the Earth’s atmosphere on a daily basis.  Particles no larger than a grain of sand comprise the majority of meteors as these specks skip across the outer reaches of the atmosphere.  While those who live well away from the bright nighttime

Meteor Burst courtesy of NASA

lights of the city may occasionally catch sight of shooting stars throughout the year, there are certain times of year in which the number and size of meteors increase to such an extent that even the city dweller stands a chance of observing a fleeting glimpse of a meteor’s path across the gaseous dome of the Earth.  As the Earth makes its way around the Sun, like clockwork its orbital path leads it through the lingering debris of comets, sometimes decades after their most recent passage, encountering these dust trails at the same point each year.  Several such phases, commonly known as meteor showers, pass with little notice; their source comets having been either too small to leave a significant supply of meteoroids, or having passed so long ago that far less material remains to noticeably increase the average nightly number of meteors.  However, there are a few meteor showers still productive enough to be worthy of note.  Of these, one of the best examples is the Perseid meteor shower, which takes place between the middle of July and the middle of August, peaking this year on the 13^th of August.

NASA Science (photo by Peter Lawrence)

The Perseids, so named because the meteors are seen from Earth as radiating from the constellation of Perseus in the northeastern sky, are the result of the comet Swift-Tuttle, a massive object nearly 17 miles wide and traveling at an astonishing 134,000 miles per hour.  Swift-Tuttle last traveled past the Earth in 1992.  In recent years, the occurrence of meteors produced by the Perseid shower has been as frequent as an average of over 170 observable meteors per hour.  Sadly, this year’s shower is not predicted to present quite so grand a display.  The expected average at its peak is only to be 100 meteors per hour.  Confounding the skygazer’s view even further is the unfortunate coincidence of a full Moon occurring very near to the day on which the Perseid shower will peak.  For those willing to play the waiting game the evenings of the 12^th or 13^th, the Moon should set with enough pre-dawn darkness remaining to allow for a higher chance of seeing a few of those spectacular fireballs streaking across the sky.

While the peak day of Perseid activity may seem like a disappointment waiting to happen, all is not lost.  A new Moon on the 31^st of July allows for a window of opportunity to see not only the pre-peak days of the Perseids, but the remaining days of the Delta Aquarid meteor shower as well.  So, if you happen to find yourselves out in the evening during the next few weeks, take a moment to gaze skyward.  You might just get a chance to see what the universe can do with something as small and seemingly insignificant as a grain of sand, as it sets the sky alight for the briefest of moments, glancing across the ceiling of the world.

Comets Meteors and Asteroids by  Seymour Simon

Stardust by Neil Gaiman

Meteor by Edmund H. North, Franklin Coen, Stanley Mann

Cosmic Phenomena: Comets, Meteor Showers, Eclipses by Gabriele Vanin

Comets and Meteor Showers by Paul P. Sipiera

Tags: Book Suggestions, Members

This entry was posted on Sunday, July 31st, 2011 at 6:52 pm and is filed under Holidays and Special Dates. You can follow any responses to this entry through the RSS 2.0 feed. You can leave a response, or trackback from your own site.