Lyrids

The Lyrids are a strong meteor shower lasting from April 16 to April 26cite web|url=http://meteorshowersonline.com/lyrids.html|title=Lyrids|publisher=Meteor Showers Online|pages=1|language=English|accessdate=2008-08-05] 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. [cite journal
last=Arter | first=T. R.
coauthors=Williams, I. P.
title=The mean orbit of the April Lyrids
journal=Monthly Notices of the Royal Astronomical Society
year=1997 | volume=289 | issue=3 | pages=721–728
url=http://adsabs.harvard.edu/abs/1997MNRAS.289..721A
accessdate=2007-11-02 ] The Lyrids have been observed for the past 2600 years.

The shower on May 22 [Some sources claims it was [http://www.google.com/search?q=%22March+16%22+%22687+BC%22+Lyrids 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.] , 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." [cite web|url=http://www.skyandtelescope.com/observing/objects/meteors/3305866.html|title=Meteors - April's Lyrid Meteor Shower|last=Sinnott|first=Roger W.|year=2008|publisher=Sky and Telescope|pages=1|language=English|accessdate=2008-08-05] (夏四月辛卯 夜 恆星不見 夜中 星隕如雨)

The shower usually peaks on around April 22 and the morning of April 23. Counts typically range from 5 to 20 meteors per hour, averaging around ten. Observers in the country will see more, observers in the city less.

Lyrid meteors are usually around magnitude +2. However, some meteors can be brighter, known as "Lyrid fireballs", cast shadows for a split second and leave behind smokey debris trails that last minutes.cite web|url=http://www.spaceweather.com/meteors/lyrids/lyrids.html|title=the Lyrid meteor shower|year=2008|publisher=spaceweather.com|pages=1|language=English|accessdate=2008-08-05]

Occasionally, the shower intensifies 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. A stronger storm ocurred in 1803, observed by a journalist in Richmond, Virginia:

"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..."

Notes and references

References and external links

* [http://science.nasa.gov/headlines/y2000/ast18apr_1m.htm April's Lyrid Meteor Shower]
* [http://www.imo.net/calendar/2007 2007 Meteor Calendar (Gary Kronk)]
* [http://ssd.jpl.nasa.gov/sbdb.cgi?sstr=2000+PN9;orb=1 NASA Orbital diagram]