Discovered by French astronomer Christian Pollas at Caussols in 1989, the asteroid was named after Toutatis from Celtic mythology.
The Chinese lunar probe Chang'e 2 flew by the asteroid at a distance of 3.2 kilometers and a relative velocity of 10.73 km/s.
[15] It remained a lost asteroid for several decades until it was rediscovered on 4 January 1989 by French astronomer Christian Pollas, and was named after the Celtic god of tribal protection Toutatis (Teutates).
It is hypothesized that Toutatis formed from two originally separate bodies which coalesced at some point (a contact binary), with the resultant asteroid being compared to a rubble pile.
[17] The asteroid may have lost most of its original angular momentum and entered into this tumbling motion as a result of the YORP effect.
The gravitational perturbations caused by frequent close approaches to the terrestrial planets lead to chaotic behavior in the orbit of Toutatis,[20] making precise long-term predictions of its location progressively inaccurate over time.
[20] Estimates in 1993 put the Lyapunov time horizon for predictability at around 50 years,[20] after which the uncertainty region becomes larger with each close approach to a planet.
[21] The low inclination (0.47°) of the orbit allows frequent transits, where the inner planets Mercury, Venus, Earth, and Mars can appear to cross the Sun as seen from the perspective of Toutatis.
[3] The approach on 29 September 2004 was particularly close, at 0.0104 AU[23] (within 4 lunar distances) from Earth, presenting a good opportunity for observation, with Toutatis having an apparent magnitude of 8.8 at its brightest.
In comparison with radar models, the proximate observations from Chang'e 2's flyby have revealed several remarkable discoveries concerning Toutatis, among which the presence of the giant basin at the big end appears to be one of the most compelling geological features, and the sharply perpendicular silhouette in the neck region that connects the head and body is also quite novel.
[14] Resolution of the radar images is as fine as 3.75 m per pixel,[30] providing data to model Toutatis's shape and spin state.