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Image courtesy Steve Ostro, NASA/JPL.
Asteroid Toutatis
Toutatis is a very odd asteroid. It appears to be two asteroids that are either loosely stuck together, rolling around against each other, or orbiting very close to one another. The orbit of Toutatis crosses Earth's orbit, periodically bringing it quite close to Earth.
Toutatis is a "yam-shaped" rock that measures 1.92 km by 2.29 km by 4.6 km (1.2 by 1.4 by 2.9 miles). The asteroid rotates in a very odd fashion. Most asteroids (and moons and planets) spin around a single axis, like a football thrown as a perfect spiral pass. Toutatis spins more like a poorly thrown, wobbly football pass. Its rotation is the result of two different types of motion with periods of 5.4 and 7.3 Earth days. If you were standing on Toutatis, the Sun and the stars would appear to cross the sky following different paths and moving at different rates on each new Toutatis 'day'.
The orbit of Toutatis brings it slightly closer to the Sun than Earth at the innermost point in its orbit (perihelion), and sends it out beyond Mars to the area of the main asteroid belt at aphelion (the point in its orbit furthest from the Sun). It takes just under four (3.98) years to orbit the Sun once. The asteroid's orbit has an eccentricity (a measure of how oval-shaped it is) of 0.6339 and a semi-major axis (size) of 2.512 AU. The orbit of Toutatis lies almost exactly in the same plane as Earth's orbit. Toutatis is classified as an Apollo group asteroid. Apollos have perihelion distances of less than one AU.
Toutatis was discovered in 1989 by a group of French astronomers led by C. Pollas. The asteroid passed 'close' to Earth on September 29, 2004. It came within 1.5 million kilometers (961 thousand miles) of Earth, about four times the distance to the Moon. No known asteroid as large as Toutatis will pass as close to Earth this century. Toutatis won't be so close again for another 500 years (in 2562). This pass brought Toutatis closer to Earth than it had been since at least the 12th century.
Toutatis is named after a god of the Celts and Gauls. Toutatis means 'king of the world', 'king of battle' or 'father of the tribe'. Toutatis was a god of war, growth and prosperity who represented the unity and the harmony of the tribe.
