Editing 4179 Toutatis (section)

== Orbit ==
[[File:Animation of 4179 Toutatis's orbit around Sun.gif|thumb|left|Animation of 4179 Toutatis's orbit around the Sun<br />{{legend2| Magenta |4179 Toutatis}}{{legend2|Yellow| Sun }}{{·}}{{legend2|RoyalBlue| Earth }}{{·}}{{legend2|Cyan| Jupiter}}]]
With a [[semimajor axis]] of 2.5294&nbsp;[[Astronomical Unit|AU]], or roughly 2.5 times the distance between Earth and the Sun, Toutatis has a 3:1 [[orbital resonance]] with Jupiter and a near-1:4 resonance with Earth making it a member of the [[Alinda asteroid]] group.<ref name="resonance" /><ref name="gravsim" /> It thus completes one orbit around the Sun for every 4.02 annual orbits of Earth. The [[gravitational perturbation]]s caused by frequent close approaches to the terrestrial planets lead to [[Chaos theory|chaotic]] behavior in the orbit of Toutatis,<ref name=Whipple1993 /> making precise long-term predictions of its location progressively inaccurate over time.<ref name=Whipple1993 /> Estimates in 1993 put the [[Lyapunov exponent|Lyapunov time horizon]] for predictability at around 50 years,<ref name=Whipple1993 /> after which the uncertainty region becomes larger with each close approach to a planet. Without the [[Perturbation (astronomy)|perturbations]] from the terrestrial planets the Lyapunov time would be close to 10,000 years.<ref name=Whipple1993 /> The initial observations that showed its chaotic behavior were made by [[Wiesław Z. Wiśniewski|Wiśniewski]].<ref>{{cite web |url=http://www.minorplanet.info/MPB/MPB_21-2.pdf |title=The Minor Planet Bulletin |publisher=Association of Lunar and Planetary Onservers |date=1994 |access-date=2014-06-25 |archive-url=https://web.archive.org/web/20130619055446/http://www.minorplanet.info/MPB/MPB_21-2.pdf |archive-date=2013-06-19 |url-status=dead }}</ref>

The low [[inclination]] (0.47°) of the orbit allows frequent [[astronomical transit|transits]], where the inner planets Mercury, Venus, Earth, and Mars can appear to cross the Sun as seen from the perspective of Toutatis. Earth did this in January 2009, July 2012, July 2016 and 2020.<ref name=transit />

=== Close approaches and collision risk ===

{| class="wikitable floatleft" style="text-align: center; margin: 1em 1em 0 0;"
|-
! colspan=3 | Close approaches<ref name=jpl-close />
|-
! Year !! AU !! [[Lunar distance (astronomy)|LD]]
|-
| 1985 || 0.28 || 109
|-
| 1988 || 0.12 || 45
|-
| 1992 || 0.02 || 9
|-
| 1996 || 0.03 || 14
|-
| 2000 || 0.07 || 29
|-
| 2004 || 0.01 || 4
|-
| 2008 || 0.05 || 20
|-
| 2012 || 0.05 || 18
|-
| 2016 || 0.25 || 98
|-
| 2065 || 0.36 || 142
|-
| 2069 || 0.02 || 8
|}

Toutatis makes frequent close approaches to Earth, with a currently minimum possible distance (Earth [[MOID]]) of just 0.006&nbsp;[[Astronomical Unit|AU]] (2.3 times as far as the [[Moon]]).<ref name=jpldata /> The approach on 29 September 2004 was particularly close, at 0.0104&nbsp;AU<ref name=neodys /> (within 4 [[lunar distance (astronomy)|lunar distances]]) from Earth, presenting a good opportunity for observation, with Toutatis having an [[apparent magnitude]] of 8.8 at its brightest.<ref name=AstDys-Toutatis2004 /> A close approach of {{convert|0.0502|AU|km mi|abbr=on|lk=on}} happened on 9 November 2008.<ref name=jpl-close /><ref name=neodys /> The most recent close approach was on 12 December 2012, at a distance of {{convert|0.046|AU|km mi|abbr=on|lk=off}},<ref name=jpl-close /><ref name=neodys /> with a magnitude of 10.7.<ref name=NEODys-Toutatis2012 /> At magnitude 10.7, Toutatis was not visible to the [[naked eye]], but just visible to experienced observers using high-end [[Binoculars#Astronomical|binoculars]]. During the 2012 encounter Toutatis was recovered on 21 May 2012, by the [[Siding Spring Survey]] at [[apparent magnitude]] 18.9.<ref name="MPC" /> A close approach will be 5 November 2069, at {{convert|0.01985|AU|km|-3|abbr=on|lk=off}}.<ref name=jpl-close />

Given that Toutatis makes many close approaches to Earth, such as in 1992, 1996, 2000, 2004, 2008, 2012, and 2016, it is listed as a [[potentially hazardous object]].<ref name=jpl-close /> With an [[Uncertainty Parameter U|uncertainty parameter]] of 0,<ref name="jpldata" /> the orbit of Toutatis is very well determined for the next few hundred years.<ref name=jpl-close /> The probability of the orbit intersecting Earth is essentially zero for at least the next six centuries.<ref name=Ostro1998 /> The likelihood of collision in the distant future is considered to be very small.<ref name=usa1993>{{cite news|url=http://findarticles.com/p/articles/mi_m1272/is_n2577_v121/ai_13953460/ |archive-url=https://archive.today/20120628224051/http://findarticles.com/p/articles/mi_m1272/is_n2577_v121/ai_13953460/ |url-status=dead |archive-date=2012-06-28 |work=USA Today (Society for the Advancement of Education) |title=Close call for earth ahead?{{Snd}} possible collision with asteroid Toutatis |date=1993 }}</ref> As a planet-crossing asteroid, Toutatis is likely to be ejected from the inner Solar System within a few million years. In 2004 a [[chain e-mail]] falsely claimed that Toutatis had a 63% chance of impacting Earth then. In fact, Toutatis passed by at 1.5 million kilometres, or about four Earth–Moon distances, as predicted.<ref name="Morrison2004" />

In 2006 Toutatis came closer than 2&nbsp;AU to Jupiter; its orbit lies inside of Jupiter's.<ref name=jpl-close /> In the 2100s, it will approach Jupiter many times at a similar distance.<ref name=jpl-close />

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{{Large near earth asteroid flybys 5LD}}
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