Killer Asteroids

Over 500 asteroids have been found that have orbits which intersect with the orbit of Earth. However, more than about 300 of the these are "lost;" they haven't been seen again since they were first discovered.

There have been several minor asteroid hits that have occured this century. These only caused local damage and hit in uninhabited areas. The biggest asteroid to hit the Earth this century was in Siberia on June 30, 1908. The rock was about 100,000 tons and the size of a large house. It shattered in the air, while about four miles from the ground, creating an explosion 2,000 times stronger than an atomic bomb! It demolished thousands of square miles of forestation.

Such impacts have scientists beginning to warn of future asteroids that could be more dangerous. Scientists who monitor asteroids in our solar system say that it's only a matter of time before a major disaster is caused by an asteroid.

Types of Asteroids

• Local
  An asteroid that is 200 yards in diameter or less has the power to cause local destruction. This types of impacts are the most common, even though they only happen 1 to 10 times every 100 years. Small asteroids can flatten vegetation and structures for hundreds of square miles if they explode in the air. Impact in water near a shoreline could cause a tidal wave or flooding.
• Widespread
  Asteroids 200 yards to 1 mile across could blast a crater up to 10 miles wide.
• "Winter"
  An asteroid the size of 1-10 miles across would create a crater up to 100 miles across! The dust which would be thrown up by such an impact could cause "winter" over the earth for several years. This would mean severe economic crisis.
• Killer
  An asteroid that is more than 10 miles in diameter could cause an ice age on the earth, and wipe out many species.

Closest Approaches

Name	Date	Distance from Earth
1994 XL1	Dec 9, 1994	65,000 miles
1993 KA2	May 20, 1993	93,000 miles
1991 BA	Jan 18, 1991	93,000 miles
4581 Asclepius	Oct 30, 1989	372,000 miles

Largest Known

Name	Diameter
Ceres	590 miles
Vesta	360 miles
Pallas	330 miles
Hygeia	269 miles

The most dangerous asteroid is one that is large enough to cause major damage, yet is small enough to not be seen until it is already very close to the earth.

Astronomer Duncan Steele, who has been trying to warn the world's governments of the danger of asteroids, describes an impact: "If a half-mile asteroid hits us, we can expect six seconds' warning. When it hits, the sky will light up like a thousand suns. By the time you've turned to look at it, it will have struck the ground, releasing energy equivalent to 10,000 times the Hiroshima bomb. Then it's goodbye."

Global Warming and the Superstorm ·  Overpopulation ·  Related Links