4179 Toutatis (asteroid 4179) is an Earth-crossing asteroid whose orbit, strongly influenced by Earth's gravity, is chaotic. Furthermore, its rotation combines two separate periodic motions that combine to produce a nonperiodic rotation; to someone on the surface of Toutatis the Sun would seem to rise and set in apparently random locations and times at the asteroid's horizon.
On September 29, 2004 Toutatis will pass within 4 lunar distances of Earth, presenting a good opportunity for observation.
Orbital characteristics Orbit type Near-Earth, chaotic[?] Semimajor axis 2.511 AU Eccentricity 0.634 Orbital period 3.98 years Inclination 0.47° Physical characteristics Diameter 4.5×2.4×1.9 km Mass 5.0×1013 kg Density 2.1 g/cm3 Rotation period 5d 9h 50m + 7d 8h 24m Spectral class S[?] Albedo 0.13 History Discoverer C. Pollas[?], 1989