Asteroids colliding with the Earth

The idea of cosmic collisions probably began with H.G. Wells's "The Star" (1897). The most famous science fiction novel featuring impact with an asteroid is Edwin Balmer's and Philip Wylie's When Worlds Collide (1933).

In their 1977 novel Lucifer's Hammer, Larry Niven and Jerry Pournelle describe the consequences of a large asteroid or meteor striking the Earth, and suggest that breaking it up into smaller pieces would increase the damage.

In his 1989 novel Nemesis, Isaac Asimov writes about a large, massive object in outer space coming dangerously close to Earth - but it is a red dwarf star, not an asteroid.

In the 1998 movie Armageddon, Bruce Willis leads a team of astronauts who must land on a large asteroid headed for Earth, and blow it up, before it collides with our planet. That same year, the film Deep Impact, starring Morgan Freeman and Robert Duvall, also dealt with an asteroid on a collision course with Earth.

Asteroids have already collided with Earth. Scientists speculate that a giant asteroid, approximately 6 miles in diameter, crashing into the Earth 65 million years ago caused the extinction of the dinosaurs. The impact kicked up vast dust clouds that covered most of the planet.

Astronomers at the Free University of Brussels have shown that a massive asteroid struck the Earth about 35 million years ago, leaving a 100-kilometer crater in Siberia. But the largest mass extinction took place 250 million years ago when a meteor the size of Mount Everest crashed into the Earth off the northwestern border of Australia, leaving a crafter 125 miles in diameter. The asteroid wiped out 70 percent of land species and 90 percent of marine species. The crash may have set off a worldwide chain of volcanic eruptions.

And just 49,000 years ago, an iron asteroid struck the surface of what is now Arizona, leaving a crater three quarters of a mild wide, and almost certainly killing any living creatures for hundreds of miles around.

In 1908, a meteor estimated to be up to 150 feet wide nearly hit the Earth's surface before burning up over Russia. The explosion was equivalent to 10 million tons of TNT - more than 750 times more powerful than the nuclear bomb that exploded over Hiroshima in World War II. It flattened hundreds of square miles of forest in Siberia.

Scientists estimate that an asteroid of this size strikes the Earth once every thousand years.

In 1996, an asteroid a third of a mile wide passed within 280,000 miles of Earth - about the same distance as between the Earth and the moon.

It was the largest object ever to pass that close, and had it hit, it would have caused an explosion in the 5,000 to 12,000 megaton range.

In March 2004, a 100-foot-long asteroid passed within 26,500 miles of our planet - the closest a passing asteroid has ever come without actually crashing into us.