Sept. 28, 2004

Gretchen Cook-Anderson 
Headquarters, Washington
(Phone: 202/358-0836) 

D.C. Agle 
Jet Propulsion Laboratory, Pasadena, Calif.
(Phone: 818/393-9011)

RELEASE: 04-319

LARGE ASTEROID WILL ZOOM SAFELY PAST EARTH WEDNESDAY

A mountain-sized asteroid will make its closest approach to Earth at 
9:35 a.m. EDT tomorrow.

Although asteroid 4179 Toutatis will come no closer than four times 
the distance between the Earth and the moon (approximately 961,000), 
this will be the closest approach of any known asteroid of comparable 
size this century. 

"This is the closest Toutatis will come for another 500 years, and its 
orbit is very well known," said Dr. Don Yeomans of NASA's Jet 
Propulsion Laboratory (JPL), Pasadena, Calif., manager of NASA's Near 
Earth Objects Program Office. "What this fly-by provides is an 
opportunity to study one of our closest solar system neighbors," he 
said.

"While we have done radar observations on this particular asteroid 
before, this is the closest it has come since at least the twelfth 
century " said Dr. Steve Ostro, a scientist at JPL. "We will use the 
huge dish in Arecibo, Puerto Rico, to refine our knowledge of its 
physical characteristics and its trajectory," he said.

Named after an obscure Celtic and Gallic god, Toutatis, the yam-shaped 
space rock measures 1.92 kilometers (1.2 miles) by 2.29 kilometers 
(1.4 miles) by 4.6 kilometers (2.9 miles). Toutatis has one of the 
strangest rotation states observed in the solar system. Instead of 
spinning around a single axis, as do the planets and the vast 
majority of asteroids, it "tumbles" somewhat like a football after a 
botched pass. Its rotation is the result of two different types of 
motion with periods of 5.4 and 7.3 Earth days that combine in such a 
way that Toutatis's orientation, with respect to the solar system, 
never repeats. 

When the asteroid flies past Earth, it will be traveling at 
approximately 39,600 kilometers per hour (24,550 mph). Toutatis has 
not passed this close to Earth since the twelfth century, and it will 
not be this close again until 2562. Toutatis was discovered in 1989.

Arecibo Observatory is operated by Cornell University, Ithaca, N.Y., 
under a cooperative agreement with the National Science Foundation, 
with support from NASA. 

To view a computer model of asteroid Toutatis on the Internet, visit: 



http://reason.jpl.nasa.gov/~ostro/ToutatisHires.mov and 

http://reason.jpl.nasa.gov/~ostro/ToutatisHires.avi

For more information about near Earth objects on the Internet, visit:



http://neo.jpl.nasa.gov/

For information about NASA on the Internet, visit:



http://www.nasa.gov

	
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