Asteroid Near Misses and Close Approaches

The Facts

Nearest approach by an asteroid since tracking began: Asteroid 2004 FU162—6150 km from surface

Number of known asteroids crossing Earth’s orbit: 1090

Number of times annually objects the size of 2009 VA skim past Earth: 2

Number of times such objects hit Earth: Once every five years

Largest known asteroid crossing Earth’s orbit: Toutatis—5 km long

Distance of Toutatis’ approach: 960,000 miles

Average interval at which moderate size asteroids (about 50 meters) impact Earth: 100 years

Most recent impact: Asteroid 2008 TC3—about 2-5 meters long

Location of 2008 TC3’s impact: Nubian desert

Largest impact in historical times: Impact of a 220 million pound asteroid in Tunguska, Siberia in 1908

Closest future approach: Asteroid Apophis, April 13, 2029, within 24,000 miles

Amazing Facts About Asteroid Near Misses

Asteroid 2004 FU162 came so close to Earth that Earth’s gravity changed the asteroid’s orbit by 20 degrees. It now will come closer to Venus than our planet.

The Tunguska asteroid did not actually reach the ground, but exploded in a massive fireball about 28,000 feet above the ground. This is evidenced by the lack of impact evidence directly below ground zero, and the direction the trees were lying—some in one direction and some in the opposite direction.

Asteroid 2008 TC3 also exploded in the atmosphere, breaking into many small meteorites, which were recovered in the Nubian desert. Thanks to modern technology and satellites, we have pictures of the event.

Most near misses are by asteroids with orbits within Earth’s orbit, such as 2004 FU162. Toutatis’ orbit, on the other hand, is highly eccentric, taking it all the way from the asteroid belt to near the Sun in a brief four year journey.

Fortunately, most near misses are not as near as near as FU 162 or TC3. Most close encounters are well outside the Moon’s orbit. But there are always those dark, surreptitious stalkers that give us just a few hours warning they are on the way.

Credits

Asteroid explosion and aftermath: NASA/JPL