4179 Toutatis, provisional designation , is an elongated, stony asteroid and slow rotator, classified as a near-Earth object and potentially hazardous asteroid of the Apollo asteroid and Alinda asteroid groups, approximately 2.5 kilometers in diameter. Discovered by French astronomer Christian Pollas at Caussols in 1989, the asteroid was named after Toutatis from Celtic mythology. Toutatis is also a Mars-crosser asteroid with a chaotic orbit produced by a 3:1 resonance with the planet Jupiter, a 1:4 resonance with the planet Earth, and frequent close approaches to the terrestrial planets, including Earth. In December 2012, Toutatis passed within about 18 lunar distances of Earth. 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. Toutatis approached Earth again in 2016, but will not make another notably close approach until 2069. Properties Toutatis was first sighted on 10 February 1934, as object 1934 CT, but lost soon afterwards. 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). The name of this god is very familiar in France due to the catchphrase Par Toutatis! by the Gauls in the comics Asterix. The spectral properties suggest that this is an S-type, or stony asteroid, consisting primarily of silicates. It has a moderate Bond albedo of 0.13. Radar imagery shows that Toutatis is a highly irregular body consisting of two distinct lobes, with maximum widths of about 4.6 km and 2.4 km, respectively. It is hypothesized that Toutatis formed from two originally separate bodies which coalesced at some point, with the resultant asteroid being compared to a rubble pile. Its rotation combines two separate periodic motions into a non-periodic result; to someone on the surface of Toutatis, the Sun would seem to rise and set in apparently random locations and at random times at the asteroid's horizon. It has a rotation period around its long axis (Pψ) of 5.38 days. This long axis is precessing with a period (Pφ) of 7.38 days. The asteroid may have lost most of its original angular momentum and entered into this tumbling motion as a result of the YORP effect. Orbit With a semimajor axis of 2.5294 AU, or roughly 2.5 times the distance between Earth and the Sun, Toutatis has a 3:1