Comet Swift–Tuttle
Comet Swift–Tuttle (109P/Swift–Tuttle) is a periodic comet with an orbital period of 133 years. It fits the classical definition of a Halley-type comet with a period between 20 and 200 years.[1] It was independently discovered by Lewis Swift and Horace Parnell Tuttle in July 1862. It has a well-known orbit and has a comet nucleus 26 km in diameter.[1]
Chinese records show that in 188 AD the comet reached apparent magnitude 0.1.[2] In 1862, the comet was as bright as Polaris.[3] The comet made a return appearance in 1992, and became visible with binoculars.[4] In 2126 it will be a bright naked-eye comet reaching about apparent magnitude 0.7.[2]
It is the parent body of the Perseid meteor shower, perhaps the best known shower and among the most reliable in performance.[5]
Near-Earth orbit
A close encounter with Earth is predicted for the comet's return to the inner Solar System in the year 4479, around Sept. 15; the closest approach is estimated to be 0.03–0.05 AU, with a probability of impact of 1×10−6, or 0.0001%.[6]
Comet Swift–Tuttle has been described as "the single most dangerous object known to humanity".[7] However, the probability of Earth impact per orbit is about a million to one against. It is estimated as 2×10−8 (0.000002%).[6] It is the largest Solar System object that makes repeated close approaches to Earth with a relative velocity of 60 km/s.[7][8]
An unusual aspect of its orbit is that it is captured into a 1:11 orbital resonance with Jupiter; it completes one orbit for every 11 of Jupiter.[6]
Comet Swift–Tuttle Media
Animation of 109P/Swift–Tuttle orbit from 1850 to 2150. Sun · Earth · Jupiter · Saturn · Uranus · 109P/Swift–Tuttle
Animation of 109P/Swift–Tuttle's close approach to Earth in 2126.
Distance of Comet Swift-Tuttle from Earth in Astronomical Units and gigametres from 800 BCE to 2500 CE. Approaches in the shaded area are not visible to the unaided eye. The dashed line shows approximately the current year.
References
- ↑ 1.0 1.1 "JPL Small-Body Database Browser: 109P/Swift–Tuttle" (last observation: 1995-03-29). Jet Propulsion Laboratory. Retrieved 2011-05-09.
- ↑ 2.0 2.1 Yau, K.; Yeomans, D.; Weissman, P. (1994). "The past and future motion of Comet P/Swift-Tuttle". Monthly Notices of the Royal Astronomical Society. 266 (2): 305–316. Bibcode:1994MNRAS.266..305Y. doi:10.1093/mnras/266.2.305.
- ↑ David Levy's guide to observing meteor showers (pg12)
- ↑ Britt, Robert (2005). Top 10 Perseid Meteor Shower Facts. Space.com. http://www.space.com/spacewatch/050811_perseid_facts.html. Retrieved 2009-08-10.
- ↑ Bedient, John. "AMS Meteor Showers page", American Meteor Society, 20 June 2010. Retrieved 2010-7-31.
- ↑ 6.0 6.1 6.2 Chambers J.E. 1995 (1995). "The long-term dynamical evolution of Comet Swift–Tuttle". Icarus. 114 (2): 372–386. Bibcode:1995Icar..114..372C. doi:10.1006/icar.1995.1069.
- ↑ 7.0 7.1 Verschuur, Gerrit L. (1997). Impact!: the threat of comets and asteroids. Oxford University Press. pp. 256 (see p. 116). ISBN 978-0-19-511919-0.
- ↑ Weissman, Paul R. (2007). "The cometary impactor flux at the Earth". In Milani, A.; Valsecchi, G.B.; Vokrouhlicky, D. (eds.). Near Earth objects, our celestial neighbors: opportunity and risk. Proceedings of the International Astronomical Union. Vol. 2. Cambridge University Press. pp. 441–450. doi:10.1017/S1743921307003559. S2CID 123279347. Archived from the original on 2009-08-15. Retrieved 2009-08-13.