Asteroid 2011 AG5
Lots of rocks are floating about in space. Some inevitably will hit the Earth though most will pass by. Asteroid 2011 AG5 has been receiving attention lately because of a very unlikely scenario which would place it on an Earth-interception course 28 years from now. As of Feb. 26, 2012, asteroid 2011 AG5 is one of 8,744 near-Earth objects that have been discovered. It is approximately 460 feet (140 meters) in size and its orbit carries it as far out as beyond Mars' orbit and as close to the sun as halfway between Earth and Venus. It was discovered on Jan. 8, 2011, by astronomers using a 60-inch Cassegrain reflector telescope located at the summit of Mount Lemmon in the Catalina Mountains north of Tucson, Arizona.
A near-Earth object is a Solar System object whose orbit brings it into close proximity with the Earth. All these objects have a closest approach of a distance less than 1.3 AU. They include a few thousand near-Earth asteroids, near-Earth comets, a number of solar-orbiting spacecraft, and meteoroids large enough to be tracked in space before striking the Earth.
Due to its current location in the daytime sky, observations of 2011 AG5 cannot be made by Earth-based telescopes, so its orbit has not yet been determined to a level where scientists can confidently project its location decades into the future.
"In September 2013, we have the opportunity to make additional observations of 2011 AG5 when it comes within 91 million miles of Earth," said Don Yeomans, manager of NASA's Near-Earth Object Program Office at the Jet Propulsion Laboratory in Pasadena, Calif. "It will be an opportunity to observe this space rock and further refine its orbit. Because of the extreme rarity of an impact by a near-Earth asteroid of this size, I fully expect we will be able to significantly reduce or rule out entirely any impact probability for the foreseeable future."
2011 AG5 will next be near Earth in February of 2023 when it will pass the planet no closer than about 1 million miles. In 2028, the asteroid will again be in the area, coming no closer than about 10.4 million miles. The Near-Earth Object Program Office states the Earth's gravitational influence on the space rock during these flybys has the potential to place the space rock on an impact course for Feb. 5, 2040, but this has very unlikely odds of occurring at 1-in-625.
This is not the only small asteroid that will come close by. Asteroid 2012 DA14 will pass within about 3.5 Earth radii of the Earth's surface on February 15, 2013. Although its size is not well determined, this near-Earth asteroid is thought to be about 45 meters in diameter. Asteroid 2012 DA14 will pass inside the geosynchronous satellite ring, located about 35,800 km above the equator.
For further information and photo: http://www.jpl.nasa.gov/asteroidwatch/newsfeatures.cfm?release=2012-051&rn=asteroid.xml&rst=2012-051