Lyrids

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April Lyrids (LYR)
Parent body C/1861 G1 (Thatcher)[1]
Radiant
Constellation Lyra
Right ascension 18h 08m[2]
Declination +32°[2]
Properties
Occurs during April 19 – April 25[2]
Date of peak April 22[2]
Velocity 48 [3] km/s
Zenithal hourly rate 10 /hr[2]
See also: List of meteor showers
Radiant point of the April Lyrid meteor shower, active each year around April 22

The April Lyrids (LYR, IAU shower number 6 [4]) are a meteor shower lasting from April 16 to April 26[5] each year. The radiant of the meteor shower is located in the constellation Lyra, near this constellation's brightest star, Alpha Lyrae (proper name Vega). Their peak is typically around April 22 each year.

The source of the meteor shower is particles of dust shed by the long-period Comet C/1861 G1 Thatcher.[1] The April Lyrids are the strongest annual shower of meteors from debris of a long-period comet, mainly because as far as other intermediate long-period comets go (200 - 10,000 years), this one has a relatively short orbital period of about 415 years. The Lyrids have been observed for the past 2600 years.

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.[5] As a result of light pollution, observers in rural areas will see more than observers in a city. Nights without a moon in the sky will reveal the most meteors. April 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.[6]

Occasionally, the shower intensifies when the planets steer the one-revolution dust trail of the comet into Earth's path, an event that happens about once every 60 years.[1] This results in an April Lyrid meteor outburst. The one-revolution dust trail is dust that has completed one orbit: the stream of dust released in the return of the comet prior to the current 1862 return.This mechanism replaces earlier ideas that the outbursts were due to a cloud of dust moving in a 60-year orbit.[7] In 1982, amateur astronomers counted 90 April Lyrids per hour at the peak and similar rates were seen in 1922. A stronger storm of up to 700 per hour occurred in 1803,[3] 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 ..."[6]

Another such outburst, and the oldest known, the shower on March 23.7,[8] 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."[9] (夏四月辛卯 夜 恆星不見 夜中 星隕如雨)

Year Lyrids active between Peak of shower ZHRmax
2007 April 16–25 April 23 21[10]
2008 waning gibbous Moon (Full moon on April 20)[11]
2009 April 16–25 April 22 15[12]
2010 April 16–25 April 22 20[13]
2011 April 22 20[14]
2012 April 16–25 April 22 and April 26 (spiked to 37 ± 21) 25/37[15]
2013 April 16–25 April 22 (Full moon April 25)[16] 22[17]
2014 April 16–25 April 22 (last quarter moon rises at 2am local time)[18] 20[19]

In the Australian Aboriginal astronomy of the Boorong tribe, the Lyrids represent the scratchings of the Mallee fowl (represented by Vega), coinciding with its nest-building season.[20]

2012 Bolide[edit]

During the 2012 shower a bolide and sonic boom rattled buildings in California and Nevada around 8AM PDT 22 April 2012.[21] The bolide air burst was likely a random unrelated meteoroid and not a member of the Lyrids shower.[22] The bolide was so bright that witnesses were seeing spots afterward.[23] The event was recorded by two infrasound monitoring stations of the Comprehensive Nuclear-Test-Ban Treaty Organization’s International Monitoring System.[24] The preliminary analysis are indicative of energy yield of approximately 4 kilotons of TNT equivalent.[24] Hiroshima's "Little Boy" had a yield of about 15 kt. The meteoroid was likely between the size of a dish washer[25] and a mini van.[26] The air burst had approximate coordinates of 37.6N, 120.5W.[27] The meteor was picked up by weather radar between Auburn, CA and Placerville, CA.[28] Robert Ward found a small CM chondrite fragment in the Henningsen Lotus Park just west of Coloma, CA on 24 April 2012.[29] The meteorite fall is now known as the Sutter's Mill meteorite. The orbit calculated by Peter Jenniskens shows this meteoroid was not a member of the April Lyrid shower.[30]

A similar event was reported in northern Guatemala around 10:22PM 30 April 2012.[31]

Notes and references[edit]

  1. ^ a b c Jenniskens, P. (2006). Meteor Showers and their Parent Comets. Cambridge University Press. p. 790. 
  2. ^ a b c d e Moore, Patrick; Rees, Robin (2011), Patrick Moore's Data Book of Astronomy (2nd ed.), Cambridge University Press, p. 275, ISBN 0521899354. 
  3. ^ a b Martinez, Patrick (1994), The Observer's Guide to Astronomy, Practical Astronomy Handbooks 2, Translated by Storm Dunlop, Cambridge University Press, p. 645, ISBN 0521458986. 
  4. ^ "IAU Meteor Data Center". p. 1. Retrieved 2013-08-06. 
  5. ^ a b "Lyrids". Meteor Showers Online. p. 1. Retrieved 2008-08-05. 
  6. ^ a b "the Lyrid meteor shower". spaceweather.com. 2008. p. 1. Retrieved 2008-08-05. 
  7. ^ 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. Bibcode:1997MNRAS.289..721A. doi:10.1093/mnras/289.3.721. 
  8. ^ M. Ed. Biot, 1841, Gatalogue General des Etoiles Filantes et des Autres Meteores Observes en Chine pendent 24 Siecles, Paris, Imprimerie Royale; P. Jenniskens, 2006, Meteor Showers and their Parent Comets, Cambridge University Press, 790 pp.
  9. ^ Sinnott, Roger W. (2008). "Meteors – April's Lyrid Meteor Shower". Sky and Telescope. p. 1. Retrieved 2008-08-05. 
  10. ^ Lyrids 2007: visual data quicklook
  11. ^ U.S. Naval Observatory Phases of the Moon 2008
  12. ^ Lyrids 2009: visual data quicklook
  13. ^ Lyrids 2010: visual data quicklook
  14. ^ Lyrids 2011: visual data quicklook
  15. ^ "Lyrids 2012: visual data quicklook". International Meteor Organization. Retrieved 2012-04-26. 
  16. ^ U.S. Naval Observatory Phases of the Moon 2013
  17. ^ "Lyrids 2013: visual data quicklook". International Meteor Organization. Retrieved 2014-04-26. 
  18. ^ Meteor Activity Outlook for April 19-25, 2014
  19. ^ "Lyrids 2014: visual data quicklook". International Meteor Organization. Retrieved 2014-04-26. 
  20. ^ Hill, Tanya; Brown, Michael J. I. (22 April 2014). "The Lyrids meteor shower should put on a show overnight". The Conversation. Retrieved 22 April 2014. 
  21. ^ Guy Clifton (April 22, 2012). "Meteor shower likely cause of big boom heard throughout region". Reno Gazette-Journal. Retrieved 2012-04-22. 
  22. ^ Deborah Byrd (April 22, 2012). "Loud boom and bright fireball over California and Nevada on April 22". EarthSky. Retrieved 2012-04-22. 
  23. ^ Guy Clifton (April 23, 2012). "Local resident's photo of Sunday's meteor goes international". Reno Gazette-Journal. Retrieved 2012-04-23. 
  24. ^ a b Guy Clifton (April 23, 2012). "Scientist says sound signal from exploding meteor lasted 18 minutes". Reno Gazette-Journal. Retrieved 2012-04-23. 
  25. ^ "Explosion Heard in NV, CA Traced To Meteor". KTVN 2 (Reno). April 22, 2012. Retrieved 2012-04-23. 
  26. ^ "Fireball Over California/Nevada: How Big Was It?". NASA/JPL. April 24, 2012. Retrieved 2012-04-24. 
  27. ^ Bill Cooke of NASA Meteoroid Environments Office (April 23, 2012). "(meteorobs) Fwd: large bolide over California/Nevada". Retrieved 2012-04-23. 
  28. ^ Marc Fries (mfries01) (23 April 2012). "Coloma, CA 22 Apr 2012 1452 UTC". Radar Obs of Meteor Events. Retrieved 2012-04-25. 
  29. ^ Franck Marchis (April 25, 2012). "Re: {MPML} Fireball Over California/Nevada: How Big Was It?". Yahoo group: Minor Planet Mailing List (mpml). Retrieved 2012-04-25. 
  30. ^ Franck Marchis (April 25, 2012). "Fragments of the daylight meteor found in California". Cosmic Diary. Retrieved 2012-04-26. 
  31. ^ "Meteorito es visto en espacio aéreo de Guatemala". elPeriodico. May 1, 2012. Retrieved 2012-05-01. 

External links[edit]