25143 Itokawa (provisional designation 1998 SF36) is a sub-kilometer near-Earth object of the Apollo group and a potentially hazardous asteroid. It was discovered by the LINEAR program in 1998 and later named after Japanese rocket engineer Hideo Itokawa. The peanut-shaped S-type asteroid has a rotation period of 12.1 hours and measures approximately 330 meters (1,100 feet) in diameter. Due to its low density and high porosity, Itokawa is considered to be a rubble pile, consisting of numerous boulders of different sizes rather than of a single solid body.
Image of Itokawa from the Hayabusa spacecraft
Schematic of Itokawa's two lobes separated from each other. Their divergent densities suggest that these were stand-alone bodies that came into contact later on, making the rubble pile also a likely contact binary.
Preliminary shape model of Itokawa based on radar observations by Goldstone and Arecibo
A near-Earth object (NEO) is any small Solar System body orbiting the Sun whose closest approach to the Sun (perihelion) is less than 1.3 times the Earth–Sun distance. This definition applies to the object's orbit around the Sun, rather than its current position, thus an object with such an orbit is considered an NEO even at times when it is far from making a close approach of Earth. If an NEO's orbit crosses the Earth's orbit, and the object is larger than 140 meters (460 ft) across, it is considered a potentially hazardous object (PHO). Most known PHOs and NEOs are asteroids, but about 0.35% are comets.
Image: Asteroid 2006DP14
Image: The VLT images the very faint Near Earth Object 2009 FD
Image: Comet Hartley 2
Radar image of (388188) 2006 DP14 recorded by a DSN antenna
