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It is the parent body of the [[Perseids|Perseid]] [[meteor shower]], perhaps the best known shower and also among the most reliable in performance.
It is the parent body of the [[Perseids|Perseid]] [[meteor shower]], perhaps the best known shower and also among the most reliable in performance.


The comet is on an orbit which will almost certainly eventually hit either the [[Earth]] or the [[Moon]], though not within this millennium.<ref>{{cite web|url=http://www.newscientist.com/article.ns?id=dn7449|title=Comet put on list of potential Earth impactors|last=Chandler|first=David L|date=2005-06-01|publisher=[[New Scientist]]|accessdate=2008-08-25}}</ref> Upon its 1992 rediscovery, the comet's date of perihelion passage was off from the then-current prediction by 17 days. It was then noticed that, if its next perihelion passage ([[August 14]], [[2126]]) was also off by another 15 days, the comet would very likely strike the Earth or Moon. Since the solid nucleus of Swift-Tuttle is about the same size as the object thought to have caused the [[Cretaceous–Tertiary extinction event]], this was of some concern. However, study of earlier passages of the comet, dating as far back as [[69 BC]], led to a recalculation of its orbit - the new orbit's stability turned out to be greater than expected, making the threat disappear.<ref>{{cite web|url=http://www.as.wvu.edu/~jel/skywatch/swfttle.html|title=on Swift-Tuttle's possible collision|last=Stephens|first=Sally|date=[[1993]]|publisher=[[Astronomical Society of the Pacific]]|accessdate=2008-08-25}}</ref>
The comet is on an orbit which will almost certainly eventually hit either the [[Earth]] or the [[Moon]], though not within this millennium.<ref>{{cite web|url=http://www.newscientist.com/article.ns?id=dn7449|title=Comet put on list of potential Earth impactors|last=Chandler|first=David L|date=2005-06-01|publisher=[[New Scientist]]|accessdate=2008-08-25}}</ref> Upon its 1992 rediscovery, the comet's date of perihelion passage was off from the then-current prediction by 17 days. It was then noticed that, if its next perihelion passage ([[August 14]], [[2126]]) was also off by another 15 days, the comet would very likely strike the Earth or Moon. Since the solid nucleus of Swift-Tuttle is about the same size as the object thought to have caused the [[Cretaceous–Tertiary extinction event]], this was of some concern. This prompted amateur astronomer and writer [[Gary W. Kronk]] to search for previous apparitions of this comet. He found the comet was most likely observed by the Chinese in 69 BC and AD 188, which was quickly confirmed by [[Brian G. Marsden]]. This information led to a recalculation of its orbit, which indicated the comet's orbit was more stable than expected, making the threat disappear.<ref>{{cite web|url=http://www.as.wvu.edu/~jel/skywatch/swfttle.html|title=on Swift-Tuttle's possible collision|last=Stephens|first=Sally|date=[[1993]]|publisher=[[Astronomical Society of the Pacific]]|accessdate=2008-08-25}}</ref>


== Notes ==
== Notes ==

Revision as of 12:14, 20 June 2009

109P/Swift-Tuttle
Discovery
Discovered byLewis Swift
Horace Parnell Tuttle
Discovery dateJuly 16, 1862
Designations
1737 N1; 1737 II; 1862 O1;
1862 III; 1992 S2; 1992 XXVIII
Orbital characteristics
EpochOctober 10, 1995 (JD 2450000.5)
Aphelion51.225 AU
Perihelion0.9595 AU
Semi-major axis26.092 AU
Eccentricity0.9632
Orbital period133.28 a
Inclination113.45°
Last perihelionDecember 11, 1992
Next perihelionJuly 12, 2126

Comet Swift-Tuttle (formally designated as 109P/Swift-Tuttle) was independently discovered by Lewis Swift on July 16, 1862 and by Horace Parnell Tuttle on July 19, 1862.

The comet made a return appearance in 1992, when it was rediscovered by Japanese astronomer Tsuruhiko Kiuchi.

It is the parent body of the Perseid meteor shower, perhaps the best known shower and also among the most reliable in performance.

The comet is on an orbit which will almost certainly eventually hit either the Earth or the Moon, though not within this millennium.[1] Upon its 1992 rediscovery, the comet's date of perihelion passage was off from the then-current prediction by 17 days. It was then noticed that, if its next perihelion passage (August 14, 2126) was also off by another 15 days, the comet would very likely strike the Earth or Moon. Since the solid nucleus of Swift-Tuttle is about the same size as the object thought to have caused the Cretaceous–Tertiary extinction event, this was of some concern. This prompted amateur astronomer and writer Gary W. Kronk to search for previous apparitions of this comet. He found the comet was most likely observed by the Chinese in 69 BC and AD 188, which was quickly confirmed by Brian G. Marsden. This information led to a recalculation of its orbit, which indicated the comet's orbit was more stable than expected, making the threat disappear.[2]

Notes

  1. ^ Chandler, David L (2005-06-01). "Comet put on list of potential Earth impactors". New Scientist. Retrieved 2008-08-25.
  2. ^ Stephens, Sally (1993). "on Swift-Tuttle's possible collision". Astronomical Society of the Pacific. Retrieved 2008-08-25. {{cite web}}: Check date values in: |date= (help)


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