Earth is entering the debris stream of Comet Swift-Tuttle and this is causing the annual Perseid Meteor Shower. The best time to watch the Perseid meteor shower might be the night/morning of August 12 - 13. The debris from Swift-Tuttle is in a wide belt of the sky and Perseid meteors are already visible. At their peak, the Perseids commonly produce 50 or more meteors per hour – in years when the moon is out of the way. The 2015 prediction is for up to 100 per hour. But remember – I am not responsible for the weather!
The Perseid meteor shower is caused by debris from Comet Swift-Tuttle. Every 133 years the huge comet swings through the inner solar system and leaves behind a trail of dust and gravel. When Earth passes through the debris, specks of comet-stuff hit the atmosphere at 140,000 mph and disintegrate in flashes of light. These meteors are called Perseids because they appear to fly out of the constellation Perseus.
The Perseid meteor shower never fails to provide an impressive display and, due to its summertime appearance, it tends to provide the majority of meteors seen by non-astronomy enthusiasts. The records of Perseid activity date to the First Century. In Chinese annals, there are observations that in 36 AD “more than 100 meteors flew thither in the morning.” Numerous references appear in Chinese, Japanese and Korean records throughout the 8th, 9th, 10th, and 11th centuries, but only sporadic references are found between the 12th and 19th centuries, inclusive. The Perseids have been referred to as the “tears of St. Lawrence,” since meteors seemed to be in abundance during the festival of that saint on August 10th, but credit for the discovery of the shower's annual appearance is given to Quételet (Brussels), who, in 1835, reported that there was a shower occurring in August that emanated from the constellation Perseus.
The first observer to provide an hourly count for this shower was Eduard Heis (Münster), who found a maximum rate of 160 meteors per hour in 1839. Observations by Heis and other observers around the world continued almost annually thereafter, with maximum rates typically falling between 37 and 88 per hour through 1858. Interestingly, the rates jumped to between 78 and 102 in 1861, according to estimates by four different observers, and, in 1863, three observers reported rates of 109 to 215 per hour. Although rates were still somewhat high in 1864, generally “normal” rates persisted throughout the remainder of the 19th-century.
In the late 1800’s Giovanni Virginio Schiaparelli established the relationship between the Perseids and comet Swift-Tuttle. This was the first time a meteor shower had been positively identified with a comet. Although the comet is nowhere near Earth, the comet's wide tail does intersect Earth's orbit. We glide through it every year in July and August. Tiny bits of comet dust hit Earth’s atmosphere traveling 132,000 mph. At that speed, even a tiny smidgen of dust makes a vivid streak of light--a meteor--when it disintegrates. The shower is most intense when Earth is in the dustiest part of the tail.
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Article by: W. Jerrold Samford, Environmental Compliance Specialist, Troutman Sanders