Simulation of Asteroid 2012 DA14 as it heads toward Earth.(Photo: NASA / JPL)
(CBS NEWS) -- As predicted, a 150-foot-wide asteroid streaked safely past Earth
Friday, making a record close approach just 17,200 miles above the
Eastern Hemisphere, well inside the orbits of geostationary
communications and weather satellites.
encounter came on the heels of a spectacular fireball over western
Siberia earlier in the day, a 10-ton meteoroid that broke up in the
atmosphere with a supersonic air blast that set off car alarms,
shattered windows and sent hundreds of people to area doctors and
hospitals with injuries from flying glass and debris.
cosmic coincidence, the meteor upstaged asteroid 2012 DA14, a much
larger, unrelated body that passed above Indonesia at 2:24 p.m EST. The
asteroid passed so close to Earth, in fact, that the planet's gravity
was expected to bend its trajectory slightly, putting it in a slightly
different orbit and reducing the chances of additional close encounters
in the foreseeable future.
"What an exciting day!" said
Paul Chodas, a scientist with NASA's Near-Earth Object program. "It's
like a shooting gallery here, we have two rare events of near-Earth
objects approaching the Earth on the same day."
asteroid was not visible to the unaided eye, but observers from Eastern
Europe to Indonesia had a chance to spot the rocky body with binoculars
or telescopes, weather permitting.
A video feed from a
telescope in Australia that was carried live on NASA's satellite
television channel showed DA14 as a quickly moving truncated streak of
light as the body's 5-mile-per-second velocity caused a slight smearing
in sequential time-exposure photographs.
The much smaller
Russian meteor was much more dramatic -- and much more dangerous -- as
the shock wave racing in its wake shattered windows along its path and
Video cameras in and around
Chelyabinsk, Russia, captured the fiery meteor as it streaked across the
sky, flaring brilliantly and casting sharp shadows as sonic booms
rocked buildings along its path.
It was not immediately
clear if any debris from the fireball made it to the surface in the form
of meteorites, but Russian authorities were investigating reports of at
least one small crater and another circular opening in an ice-covered
lake that may be related.
Scientists believe the meteor was a body about 50 feet or so across, or about one third the presumed size of 2012 DA14.
so, "you can see what sort of destruction and shock wave a smaller
asteroid can produce," Chodas said. "It's like Mother Nature is showing
us what a tiny one, really, can do. And DA14 is only a small asteroid on
Speaking on NASA's satellite television
channel, Chodas said the meteor and asteroid 2012 DA14 were on different
trajectories and "it's simply a coincidence they happened to hit and
come near the Earth the same day."
But the meteor and the
asteroid flyby highlighted the threat posed by debris left over from
the formation of the solar system 4.6 billion years ago.
the odds of a major asteroid impact in any given year are low, the
consequences could be extreme, prompting ongoing work by NASA and other
agencies to identify near-Earth asteroids that could one day pose a
threat to the planet.
Since dedicated surveys began some
15 years ago, astronomers have catalogued nearly 10,000 near-Earth
asteroids, including about a thousand big enough to cause global damage
in a collision.
2012 DA14 is believed to measure about 150 feet across. It was moving at nearly 5 miles per second when it streaked past Earth.
similar but slightly smaller rocky asteroid is believed to have crashed
into the atmosphere above Siberia in June 1908, disintegrating in an
air blast known as the Tunguska Event that leveled millions of trees
over more than 800 square miles.
A denser, 150-foot-wide
nickel-iron asteroid blasted through the atmosphere above Arizona 50,000
years ago, excavating Meteor Crater, a mile-wide impact basin similar
in appearance to those on the moon.
Don Yeomans, an
asteroid expert at NASA's Jet Propulsion Laboratory, said 2012 DA14
likely would have broken up in the atmosphere had it hit the planet,
releasing some 2.4 megatons of energy in the resulting air blast. That's
roughly 150 times the 16-kiloton atomic bomb blast above Hiroshima in
Asteroid collisions with Earth are not uncommon,
but most of the 100 tons of debris that hit the atmosphere every day is
made up of small objects, burning up unseen at high altitude. Objects
the size of basketballs impact daily, with car-size objects hitting
every few weeks.
Yeomans said asteroids the size of 2012
DA14 could be expected to impact the planet once every 1,200 years on
average. He said bodies large enough to trigger a global catastrophe,
like the six-mile-wide asteroid believed to have wiped out the
dinosaurs, hit every hundred million years or so.