Lyrids
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The Lyrids are a strong meteor shower lasting from April 15 to April 28 each year. The radiant of the meteor shower is located in the constellation Lyra, peaking at April 22—hence they are also called the Alpha Lyrids or April Lyrids. The source of the meteor shower is the periodic Comet C/1861 G1 Thatcher.[1] The Lyrids have been observed for the past 2600 years.
The shower on May 22[2], 687 BC (proleptic Julian calendar) was recorded in Zuo Zhuan, which describes the shower as "On day xīn-mǎo of month 4 in the summer (of year 7 of King Zhuang of Lu), at night, fixed stars are invisible, at midnight, stars dropped down like rain." (夏四月辛卯 夜 恆星不見 夜中 星隕如雨)
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Every year in late April Earth passes through the dusty tail of Comet Thatcher (C/1861 G1), and the encounter causes the Lyrid meteor shower.
The best time of year to look is during the hours before dawn on the the night of April 22 and the morning of April 23, 2008. Typical maximum of the shower is between 2am and sunrise. Counts typically range from 5 to 20 meteors per hour. Observers in the country will see more, observers in the city less.
The radiant of the shower is located near the bright star Vega. The shower, however, is actually caused by Comet Thatcher's dust trail.
Lyrid meteors are typically as bright as the stars in the Big Dipper[citation needed]. However, some meteors can be brighter, known as "Lyrid fireballs", cast shadows for a split second and leave behind smokey debris trails that linger for minutes.
Occasionally, the shower intensifies. Most years in April there are no more than 5 to 20 meteors per hour during the shower's peak. Occasionally, the showers can become more intense than usual when the Earth passes through a thicker part of the dust trail, resulting in a Lyrid meteor storm. In 1982, amateur astromomers counted 90 Lyrids per hour. An even more impressive outburst was documented in 1803 by a journalist in Richmond, Virginia, who wrote:
"Shooting stars. This electrical [sic] phenomenon was observed on Wednesday morning last at Richmond and its vicinity, in a manner that alarmed many, and astonished every person that beheld it. From one until three in the morning, those starry meteors seemed to fall from every point in the heavens, in such numbers as to resemble a shower of sky rockets..."
[edit] Notes and references
- ^ Arter, T. R.; Williams, I. P. (1997). "The mean orbit of the April Lyrids". Monthly Notices of the Royal Astronomical Society 289 (3): 721–728.
- ^ Some sources claims it was March 16, which can't be right. First, March 16 they claimed was actually in proleptic Gregorian calendar; Second, it was not in summer as original text have described clearly.
