Asteroid Toutatis to shoot past Earth

Skywatchers can watch as this rocky minor body misses Earth by nearly one million miles.
By | Published: September 27, 2004 | Last updated on May 18, 2023

For more information on Toutatis, as well as other upcoming sky events, please see the October 2004 issue of Astronomy magazine. More Toutatis facts
Officially designated asteroid 4179, Toutatis is a rocky body measuring 3 by 1.5 miles (4.5 by 2.4 km). French astronomer Christian Pollas at Observatoire de la Côte d’Azur discovered it on January 4, 1989.

Toutatis, the name of a Celtic god of war, means “father of the tribe.”

For more information, contact:
Matthew Quandt
Assistant editor
262.796.8776 x.419

September 27, 2004

WAUKESHA, WISCONSIN: On September 29, Toutatis will pass close to Earth, at least by astronomical standards. Heading toward our location in space at 22,000 miles per hour (35,000 kilometers/hour), Toutatis will pass about 960,000 miles (1.5 million km) from Earth.

Toutatis will not hit Earth. If Toutatis did hit Earth, it would create a blast with the energy equivalent to 1 million megatons of TNT.

Toutatis makes a roughly 4-year (1,430.9-day) trek around the Sun that takes it from just inside Earth’s orbit to outside the orbit of Mars. Because both Earth and Toutatis are in continual motion, the distance separating them at closest approach every 4 years varies greatly. This year’s approach will be the asteroid’s closest pass since 1353. Toutatis won’t swing this close again until 2562.

On September 29 — the date of its closest approach — Toutatis will be 250 times brighter than it was July 29. Still, it will be only a point of light shining 16 times dimmer than the faintest stars visible to the unaided eye. Toutatis rates magnitude 9 on the brightness scale astronomers use. Most people can see to magnitude 6. Normally, binoculars would allow you to see Toutatis from a location away from city lights, but September 29, the Moon is nearly full and the sky won’t be dark anywhere. Also, no observer in Denver, Kansas City, or Pittsburgh — or in any location north of these cities — will be able to see the asteroid then because it will be below the horizon.

At close approach, Toutatis will be in front of the stars of the southern constellation Centaurus. Southern Hemisphere observers using 6-inch or larger telescopes will be able to follow the asteroid’s amazingly fast motion across the sky — almost three Moon widths in an hour.