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4179 Toutatis

4179 Toutatis
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
Discoverer C. Pollas, 1989

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.