A newly discovered asteroid, 2010 GA6, will safely fly by Earth April 8th at 4:06 p.m. Pacific (23:06 U.T.C.). At the time of the closest approach 2010 GA6 will be about 223,000 miles away from Earth - about 9/10ths the distance to the moon. The asteroid, approximately 71 feet wide, was discovered by the Catalina Sky Survey located in Tucson, Arizona. Asteroids, sometimes called minor planets or planetoids, are small Solar System bodies in orbit around the Sun; they are smaller than planets but larger than meteoroids. Such an object, if it hit the Earth, would have a major impact.
Space is nearly empty but in many ways it is filled with flying junk of which asteroids, meteors, and comets are examples.
"Fly bys of Near Earth objects within the moon's orbit occur every few weeks," said Don Yeomans of NASA's Near Earth Object Office at the Jet Propulsion Laboratory in Pasadena, Calif.
NASA detects and tracks asteroids and comets passing close to Earth using both ground and space based telescopes. The Near Earth Object Observations Program, commonly called "Spaceguard," discovers these objects, characterizes a subset of them and plots their orbits to determine if any could be potentially hazardous to our planet.
The vast majority of known asteroids orbit within the main asteroid belt between the orbits of Mars and Jupiter, generally in relatively low eccentricity (i.e., not very elongated) orbits. This belt is currently estimated to contain between 1.1 and 1.9 million asteroids larger than 0.6 mile in diameter, and millions of smaller ones. It is thought that these asteroids are remnants of the protoplanetary disk, and in this region the accretion of planetesimals into planets during the formative period of the solar system was prevented by large gravitational perturbations by Jupiter.
Although fewer Trojan asteroids sharing Jupiter's orbit are currently known, it is thought that there are as many as there are asteroids in the main belt.
Various classes of asteroid have been discovered outside the main asteroid belt. Near Earth asteroids have orbits in the vicinity of Earth's orbit. Trojan asteroids are gravitationally locked into synchronization with Jupiter, either leading or trailing the planet in its orbit. A couple Trojans have been found orbiting with Mars. A group of asteroids called Vulcanoids are hypothesized by some to lie very close to the Sun, within the orbit of Mercury, but none has so far been found.
The Apollo asteroids are a group of near-Earth asteroids named after 1862 Apollo, the first asteroid of this group to be discovered by Karl Wilhelm Reinmuth. They are asteroids that cross the Earth orbital path. Some can get very close to the Earth, making them a potential threat to our planet.
The largest known Apollo asteroid is 1866 Sisyphus, with a diameter of about 10 km.
For further information: http://www.jpl.nasa.gov/news/news.cfm?release=2010-115&rn=news.xml&rst=2549 or http://en.wikipedia.org/wiki/Asteroid