YU55 will pass near Earth on Nov. 8, scientists say
Purdue Scientist Estimates Impact Of Large Object.

Though there's no threat that it will strike Earth, a large asteroid that will pass close to the planet on Nov. 8 would have had a devastating effect if it were to hit the planet, experts said.

The aircraft carrier-sized asteroid, known as YU55, was discovered in 2005. At its closest approach, scientists project it will be 201,000 from Earth.

The near-miss is a reminder of how fragile the planet is.

Jay Melosh, a professor of earth and atmospheric sciences at Purdue University, said the impact of an object of similar size would be catastrophic, producing an earthquake of magnitude 7.0, prospects of a 70-foot tsunami and worse.

"What is unique about this asteroid flyby is that we were aware of it well in advance," Melosh said. "Before about 1980 we wouldn't know about an asteroid of this size until it was already making a close pass, but now it is unlikely that such an asteroid will approach the Earth without our knowledge."

NASA and Spacewatch monitor near-Earth objects that are 0.6 mile or larger in diameter. The close approach of the asteroid has been expected since 2005, when it was discovered.

Scientists at Purdue put together a calculator, called Impact Earth to estimate the impact of an object striking Earth, approximating the type of damage it could cause.

The calculator estimated that if YU55 hit Earth, a 1,700-foot-deep crater four miles in diameter would be created and that humans would endure extensive first-degree burns 60 miles away from the point of impact.

An object the size of YU55 would destroy a large city if it took a direct hit.

NASA said the last time an asteroid of a similar size came close to hitting Earth was in 1976, and that a known large asteroid will be near the planet in 2028.

Earth is scarred by craters scientists believe were created by similar-sized objects, including craters in Alabama and Wisconsin, Melosh said.

"Impacts from asteroids of this size are very rare," he said. "They occur about once every 100,000 years, so the chances of an actual collision with an asteroid like YU55 is about 1 percent in the next thousand years."

Scientists believe that an asteroid that is about a third of a mile wide has a small chance of hitting Earth in 2036.