|
Summer 2004 Issue |
|
Fig 1. Location in the
sky of the Perseid meteor shower. |
PROPAGATION By Tomas Hood, NW7US/AAAØWA The Perseid Shower Looks Promising |
|
Lewis Swift and Horace Tuttle, Americans working independently, discovered a comet in August 1862. Three years later, Giovanni Schiaparelli (of Martian “canali” fame) realized it was the source of the August Perseid meteors. The comet, known now as Comet Swift-Tuttle, leaves a trail of dust that Earth passes through during August. This year’s Perseid shower promises to be more rewarding than before due to a relatively new filament ribbon trail of dust that drifted into the Earth’s path. This trail boiled off the comet in 1862, during the Civil War. The main trail is older and more dispersed, and responsible for the month-long shower that peaks on August 12. Perseids favor northern latitudes. Because of the way Comet Swift-Tuttle’s orbit is tilted, its dust falls on Earth’s Northern Hemisphere. Meteors stream out of the constellation Perseus, which is barely visible south of the equator. The Perseid shower begins slowly in mid-July, featuring dust-size meteoroids hitting the atmosphere. As we get closer to August 12, the rate builds. Now, with this new ribbon, we can expect dozens, possibly even hundreds, of meteors per hour. For working VHF/UHF meteor scatter, this could prove to be an exciting event. According to predictions, Earth will plow through the filament at 2100 UTC, Wednesday, August 11, 2004 (5 PM EDT). Most of the activity will be over Europe and Asia, with a possible visual rate of as many as 200 meteors per hour (see Figure 1). Later that night, North American observers and radio operators can expect most of the activity to be from the older dust from Swift-Tuttle, at a visual rate of about 40 to 60 meteors per hour, some of them intense.
The best time for working the Perseid VHF/UHF
meteor scatter in North America is during the hours before dawn on
Thursday, August 12. As early as midnight, but more likely at around 2 AM
local time, you’ll soon be working stations via the ionization caused by
the heat of burning-up dust. (A good web resource on the Perseid meteor
shower is <http://comets. amsmeteors.org/meteors/showers/perseids.html>). Click here to return to Summer 2004 highlights Click here to subscribe to VHF _________________ © Copyright 2004, CQ Communications, Inc. All rights reserved. This material may not be reproduced or republished, including posting to a website, in part or in whole, by any means, without the express written permission of the publisher, CQ Communications, Inc. Hyperlinks to this page are permitted.
|
|