Toutatis is a 5,500 million pound asteroid measuring 5 kilometers in length. This near earth asteroid is making its closes passes to Earth every 4 years.
In 2004 the asteriod came within 1.5 million kilometers (960,000 miles) of Earth, or four times the Earth-moon distance.
Were Toutatis to collide with Earth, the energy released would be equivalent to tens of thousands of hydrogen bombs, kicking up dust clouds which would shield out the sunlight, plunging the planet and all its inhabitants into a lethal "impact winter."
Earth's atmosphere protects us from NEOs up to a diameter of 40m (130 feet), an impact energy of about three megatonnes. Beyond that size, the news is bad. NEOs between 40m and one km (0.6 of a mile) across can inflict local damage equivalent to thousands of nuclear bombs, as evidenced by the massive explosion in Tanguska, Siberia in 1908.
Date 1992 Dec 8 - Distance 2,244,774 miles / 3,612,552 km
Date 1996 Nov 29 - Distance 3,293,452 miles / 5,300,298 km
Date 2000 Oct 31 - Distance 6,866,209 miles / 11,050,092 km
Date 2004 Sep 29 Distance 962,951 miles / 1,549,719 km
Date 2008 [missing data]
Date 2012 Dec 12 Distance 4,307,000 miles
The Sep. 29, 2004, approach is the closest in this century of any known asteroid at least as large as Toutatis (or more precisely, of any known asteroid with an absolute magnitude as small as H = 15.30).
The most recent close approach of 0.0502 AU happened on November 9, 2008. The next close approach will be December 12, 2012, at a distance of 0.046 AU, and at magnitude 10.
There are thought to be more than 300,000 nearby small asteroids (asteroids about 100 meters across). Such asteroids should statistically hit Earth once every few thousand years. The most recent such asteroid strike occurred in 1908, when an asteroid measuring about 60 meters in diameter hit Russia. The "Tunguska" bolide exploded in the atmosphere and flattened about 700 square miles of Siberian forest.
One consequence of the asteroid's frequent close approaches to Earth is that its trajectory cannot be predicted accurately. In fact, of all the Earth-crossing asteroids, the orbit of Toutatis is thought to be one of the most chaotic.
Two NASA-sponsored scientists studying the Earth- crossing asteroid 4179 Toutatis with radio telescopes have found it to be one of the strangest objects in the solar system, with a highly irregular shape and an extraordinarily complex "tumbling" rotation.