Meteoroids are the smallest particles orbiting the sun, and most are no larger than grains of sand. From years of studying the evolution of meteor streams, astronomers have concluded that clouds of meteoroids orbiting the sun were produced by comets. Meteoroids can not be observed moving through space because of their small size. Over the years numerous man-made satellites recovered by manned spacecraft have shown pits in their metal skins which were caused by the impact of meteoroids.
Meteoroids become visible to observers on Earth when they enter Earth's atmosphere. They are then referred to as meteors. They become visible as a result of friction caused by air molecules slamming against the surface of the high-velocity particle. The friction typically causes meteors to glow blue or white, although other colors have been reported. Most meteors completely burn up in the atmosphere at altitudes of between 60 and 80 miles. They are rarely seen for periods of more than a few seconds.
Occasionally, a large meteor will not burn up completely as it moves through Earth's atmosphere. The subsequent pieces that fall to Earth's surface are known as meteorites.
The source of the Perseid shower is comet 109P/Swift-Tuttle, which orbits the Sun in a long, roughly 130-year ellipse. The comet sheds bits of its material each time it returns near the Sun. This debris keeps traveling along near the comet's orbital path, creating a sparse "river of rubble" in space.
Source of the above information: Sky & Telescope magazine and other websites.
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Star trails instead of Perseids ... August 12, 2007 01:09 - 02:36 UT. I set out to catch Perseids, but captured none, alas. The peak of the Perseids is during the night of August 12-13, but this year [2007] the weather forecast was bad, so I decided to try my luck the night before. And indeed: during the night of August 12-13, 2007 I was clouded out. Imaging Details: TV zoom lens at 10mm, SC3a b/w RAW camera mounted on static tripod; exposure 247 x 30 seconds I wanted to image in unattended mode during the whole night, but when I left my observatory I habitually shut off the mains power, and after a while my laptop batteries gave up. At 01:00 UT I woke up and went outside expecting that all was still working; I soon found out what had happened, so I reconnected to the mains and restarted the imaging. In the morning I found out that I had not captured any Perseids, but summing in K3CCDTools in if-lighter mode still yields a nice image. More star trails. |
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August 12, 2004 01:08 UT A Perseid meteor. |
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August 12, 2004 01:08 UT A 5 frame animation of the beginning and the end of a Perseid meteor. WARNING: it might take some time to load the large images, as the animation is almost 800Kb. |
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Some details about the imaging. 50mm f/1.8 SLR Photolens stopped down 2 stops at f/4, Camera:Vesta SC3abwRAW on static tripod, Baader Infra Red Blocking Filter, exposure 2 seconds. Camera settings: 5fps, brightness 50, gamma 100, white balance: automatic; gain 100.
I aimed high in the skies in such a way that there were no trees in my field of view.
Resulting AVI's: Reminder for myself: next opportunity to image meteors I should use a 'wider' lens, maybe the orignal Vesta/ToUcam lens and use a 10 seconds exposure. When the next meteor shower will take place you can figure out here !
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