Asteroid 2055 YU55 passes close by Earth; how close did it get?
Wednesday, November 9, 3:01 PM

An asteroid that scientists have been watching and awaiting for years passed
close to Earth on Tueday night, but how close a call was it? As Elizabeth Flock
reported:

An asteroid the size of an aircraft carrier missed Earth by only 200,000 miles
as it flew by Tuesday night  the closest an asteroid has been to Earth in
200 years

Asteroid 2005 YU55, as it has been dubbed, streaked by at about 30,000 mph, but
some scientists and lucky amateur astronomers caught a glimpse in their
telescopes, where they saw strange structures on the asteroid\u2019s
dark-colored surface.

Scientists around the world took the opportunity to get a close look at the
asteroid and examine it for traces of water. As AP explained:

Scientists at NASA's Deep Space Network in the California desert have
tracked the quarter-mile-wide asteroid since last week as it approached from the
direction of the sun at 29,000 mph.

Astronomers and amateur skygazers around the world kept watch, too.

The Clay Center Observatory in Brookline, Mass., planned an all-night viewing
party so children and parents could peer through research-grade telescopes and
listen to lectures. The asteroid can't be detected with the naked eye.

For those without a telescope, the observatory streamed video of the flyby live
on Ustream, attracting several thousand viewers. The asteroid appeared as a
white dot against a backdrop of stars.

It's a fantastic opportunity to educate the public that there are
things out in space that we need to be aware of,\u201d including this latest
flyby, said observatory director Ron Dantowitz.

Dantowitz added: It will miss the Earth. We try to mention that in every
breath.

Since its discovery six years ago, scientists have been monitoring the
spherical, coal-colored asteroid as it slowly spins through space and were
confident it posed no danger.

Asteroids are leftovers from the formation of the solar system some 4.5 billion
years ago. Scientists believe their growth was stunted by Jupiter\u2019s
gravitational pull and never had the chance to become full-fledged planets.
Pieces of asteroids periodically break off and make fiery plunges through the
atmosphere as meteorites.

Don Yeomans, who heads NASA's Near Earth Object Program, said 2005 YU55 is
the type of asteroid that humans may want to visit because it contains
carbon-based materials and possibly frozen water.

With the space shuttle program retired, the Obama administration wants
astronauts to land on an asteroid as a stepping stone to Mars.

What would happen if an asteroid the size of 2005 YU55 hit the Earth? Brad
Plumer explained the potential damage and a nifty tool for estimating asteroid
impact damage.

Jay Melosh, an atmospheric scientist at Purdue, has created a nifty little
impact calculator that lets you figure out the consequences of a
large asteroid hitting the Earth. If the asteroid of the moment, YU55, were to
enter the Earth's atmosphere at 11 miles per second, it would burn up, and
the remaining chunks would, on impact, create a crater four miles wide and 1,700
feet deep.

Sixty miles away from the impact site the heat from the fireball would
cause extensive first-degree burns,\u201d the Purdue team notes. The
seismic shaking would knock down chimneys and the blast wave would shatter glass
windows. The asteroid could technically wipe out a city the size of
Chicago, although the chances of hitting a city are pretty small. If it landed
in the ocean, it would create tsunami waves 60 feet high.

Fortunately, we probably don't have to worry about another asteroid this
size moseying near Earth until 2028. NASA's Near Earth Object program has
been tracking objects in our vicinity that are more than six-tenths of a mile in
diameter the dangerous ones, basically and now claim to have
discovered more than 90 percent of them. Of course, sometimes these objects can
creep up pretty quickly: YU55 was only discovered in 2005, by the University of
Arizona's Spacewatch Project.