Of Shooting Stars

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The Fallen Sky: An Intimate History of Shooting Stars
Cover Courtesy & Copyright © 2009 The Penguin Group

Holly: Hi, I’m Holly Strand from Stokes Nature Center in beautiful Logan Canyon.

Christopher Cokinos is the author of a new book, The Fallen Sky, published by the Penguin Group Press. It’s the story of meteorites and the impressions that meteorites make on the Earth and in the people who seek them out. Here’s Chris talking about falling stars:

Chris: On any clear night, under a dark enough sky, we can see shooting stars. We wish upon them even if we may not know what they are. It’s as if we’re eager to pin our chances on something strange and sudden.

A shooting star is not a star; it’s a meteor—the bright passage of a small grain or rock burning up through the air as it descends from space. If it’s big enough, it may drop a rock on the Earth itself—then it becomes a meteorite. In space, these objects are called meteoroids.

Every mid-August, our skies are graced by a shower of shooting stars—the Perseids. This is when Earth intersects the spindrift tail of the disintegrated Comet Swift-Tuttle, and we see these dusty grains streaking through the sky, too small to ever reach us.

They’re called the Perseids because the meteors appear to originate from the constellation Perseus, but these shooting stars can appear in any part of the sky.

Meteors travel very fast, from between 7 miles per second to 44 miles per second, and even one the size of a raisin can produce a huge fireball.

But if you see one that big during the Perseids, it’s not a Perseid—it’s a random meteor, originating from the asteroid belt or even the Moon or Mars.

This year, the moon will interfere with viewing the shower, but you can still see quite a few Perseids from the late evening of August 11 through the morning of August 12.

The best way to watch is to recline on the ground or on a chaise so you have a wide view of the sky, preferably away from city lights. Have snacks, water and appropriate clothing and maybe some bug spray. Don’t use binoculars or a telescope as they restrict your field of view.

To learn how to make simple but scientifically useful observations, go to the American Meteor Society website at www.amsmeteors.org.

Of course, though it may not be scientifically useful, when you see a shooting star—feel free to make a wish.

Holly: Thanks, Chris. For listeners in the Logan area, check out the Star Party at the American West Heritage Center on August 14th. For more details see awhc.org

For Wild About Utah and Stokes Nature Center, I’m Holly Strand.

Credits:

Image: Book Cover Courtesy & Copyright © 2009 The Penguin Group

Text: Chris Cokinos

Sources & Additional Reading:

Cokinos, Christopher. 2009. The Fallen Sky: An Intimate History of Shooting Stars. Penguin Group, Inc.

“Weaving natural history, memoir, and the stories of maverick scientists, daring adventurers, and stargazing dreamers, this epic work takes us from Antarctica to outer space to tell the tale of how the study of meteorites became a scientific passion.”

https://www.amazon.com/Fallen-Sky-Intimate-History-Shooting/dp/1585428329 (Accessed August 11, 2009)

http://www.amazon.com/Fallen-Sky-Intimate-History-Shooting/dp/1585427209

Perseids Meteor Shower

The Perseids meteor shower is one of the most popular events of the year for sky watchers. A meteor shower is simply an increase in meteor activity which is produced when the Earth passes through a trail of debris that is also in orbit about the Sun.

Perseids debris comes from the Comet Swift-Tuttle, the largest object known to make repeated passes near the Earth. Its nucleus is about 6 miles across. Most of its meteoroids are the size of sand grains; a few are as big as peas or marbles. When they enter Earth’s atmosphere, they are called meteors. Almost none hit the ground, but if one does, it’s called a meteorite.

The Perseid shower is detectable from July 25-Aug 20, but meteor activity rises sharply around Aug. 12. For example, on the 25th you can expect to see a meteor every hour. Maybe 5 an hour by the 1st of August, up to 15 an hour by August 10th. But then on August 12, the number will spike to 50 -80 /hour and in some years up to 200! Then the number will quickly subside until Aug 20, when you’ll be back to 1 an hour.

Perseid meteoroids are fast. They enter Earth’s atmosphere at roughly 133,000 mph– or 60 km per second. They also make a sound! Fast-moving meteoroids ionize the air in their path leaving behind a trail that can briefly reflect radio wave from TV stations, RADAR facilities or AM/FM transmitters. A “radio meteor” is the short-lived echo of a radio signal that bounces off such a trail. Scientists at the NASA Marshall Space Flight Center in Huntsville, AL have established a radio meteor monitoring system. Here’s what a typical echo sounds like against some background static:

http://www.spaceweather.com/meteors/audio/geminidecho.wav

Hmmm… Kind of reminds me of a whale song.

This year, August 12th features a gibbous moon which means lunar glare will wipe out the path of the smaller meteroids . You’ll want to find a spot in the moonshade which will minimize glare. Or you can watch during predawn moonless hours on August 12th which will be the peak of this year’s show. No worries for those of us who can’t stay awake past midnight though. There will still be so-called shooting stars even while the moon is out—just less than when the moon has set. Furthermore, Jupiter is almost opposite to the sun with the planet coming physically closest to the Earth in its orbit . That means good viewing as Jupiter will appear very large. Look for it together with the moon in the constellation Sagittarius in the southeast sky. Depending upon your viewing equipment, you may be able to see some of Jupiter’s moons as well as the Great Red Spot, which is a gigantic hurricane-like storm twice the size of Earth on Jupiter’s surface.

For a sociable viewing experience, sky watchers in Northern Utah are invited to the Stokes Nature Center/American West Heritage Center Star Party August 12th from 9-1. We’ll have powerful telescopes, experienced interpreters, and all sorts of fun activities for adults and families. For more information see www.logannature.org or www.awhc.org

Credits:

Photo: Courtesy Science.NASA.gov: http://science.nasa.gov/headlines/y2006/07aug_perseids.htm

Text: Stokes Nature Center:

Sources & Additional Reading

Pop! Ping! Perseids! Science@NASA (accessed July 31, 2008)
http://science.nasa.gov/newhome/headlines/ast13aug99_1.htm

Philipps, Tony. 2008. The 2008 Perseid Meteor Shower Science@NASA (accessed July 31, 2008)

Radio Meteor Listening.
http://www.spaceweather.com/glossary/forwardscatter.html (accessed July 31, 2008)

Ridpath, Ian. Oxford Dictionary of Astronomy. 1997.
NY: Oxford University Press