SPACE.com -- Discovery: Asteroid Found Roaming Within Earth's Solar Orbit

Asteroid 2003 CP20 carves a highly inclined path around the Sun that is entirely within Earth's orbit. This map shows locations of the asteroid and the inner planets on Feb. 14, 2003.

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	Discovery: Asteroid Found Roaming Within Earth's Solar Orbit By Robert Roy Britt Senior Science Writer posted: 12:07 pm ET 14 February 2003

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The first object other than Venus or Mercury to circle the Sun entirely inside Earth's solar orbit has been discovered. The asteroid may be one of many that inhabit that difficult-to-examine region of space.

Most asteroids -- many millions of them -- travel in a belt between Mars and Jupiter. Hundreds have been found wandering through the inner solar system, however, but until now all were on elongated orbits that took them back out at least beyond the orbit of Earth.

The newfound object is named 2003 CP20. Based on its brightness, it is estimated to be more than 0.6 miles wide (1 km). This is the minimum threshold for space rocks that might cause global destruction were one to hit Earth, experts say. But astronomers said this one poses no danger.

The asteroid is too far away and too dim to be seen from Earth without the use of good-sized telescopes.

It was discovered earlier this week by the Lincoln Near Earth Asteroid Research (LINEAR) project at MIT. The asteroid hunting program is funded by the U.S. Air Force and NASA. The discovery was announced Thursday in an electronic circular put out by the Minor Planet Center at the Smithsonian Astrophysical Observatory in Cambridge, MA.

Like most asteroids and even planets, this one does not carve a perfectly circular orbit. Officials at the center said the asteroid's greatest distance from the Sun, though, is less than the Earth's closest distance. The asteroid's trajectory is highly inclined, going above and below the imaginary plane in space through which Earth moves around the Sun.

Current estimates show that 2003 CP20 can't come closer to Earth than 17.7 million miles (28.4 million km). It will pass within 4.65 million miles (7.48 million km) of Venus more than once, however. For perspective, the Moon is about 238,900 miles (384,402 km) from Earth.

Spotting asteroids is tricky business. Last June, an asteroid passed within 75,000 miles (119,229 kilometers) of Earth and was not spotted until three days later.

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