Russian meteorite blast explained: Fireball explosion, not meteor shower
RT,
15
February, 2013
A
Russian policeman works near an ice hole, said by the Interior
Ministry department for Chelyabinsk region to be the point of impact
of a meteor seen earlier in the Urals region, at lake Chebarkul some
80 kilometers (50 miles) west of Chelyabinsk February 15, 2013
(Reuters / Chelyabinsk region Interior Ministry)
Russian
scientists are investigating the meteorite explosion in the Ural’s
region, which injured nearly 1200 people on Friday. They explained
the nature of the celestial body that the state space agency had
failed to track down on time.
The
object was identified as a solitary 10 ton bolide by the Russian
Academy of Sciences (RAN). Bolides or bright fireballs are large
meteors that explode in the lower atmosphere, and unlike meteorite
showers they can be dangerous, scientists explained.
The
Chelyabinsk fireball entered the atmosphere moving at a speed of
about 20 km/s. The body of several meters in diameter then burst into
pieces at the height of 30-50 km above the ground, RAN reported.
Three
consecutive explosions shattered the body further. Large fragments
moving at high speed caused a powerful flash and a strong blast wave,
with most energy released at a height of 5 to 15 km, RAN added.
The
impact and the sound of the blast reached the ground minutes after
the explosion, causing havoc and panic in Chelyabinsk. While most of
the object burned down during the fall, the remaining parts showered
over the region, possibly adding to the damage and injuries.
The
actual power of the blast is still being discussed, with some
scientists estimating it as low as 0.1 kilotons and others saying it
could be more than 10 kilotons, depending on the height the explosion
was registered. Conflicting reports also centered on the trajectory
of the falling body.
The
combustion products won’t stay in the atmosphere for long, and will
soon come down with precipitation, Russian scientists said. The
meteorite is believed to have caused no significant pollution, but
the elements it emitted could only be identified after studying its
fragments, they added. So far, RAN and Emergency services have denied
the possibility of radioactive pollution.
Russian
space agency Roscosmos earlier admitted they did not track the
meteorite that fell near Chelyabinsk, although several other flybys
were detected by Roshydromet overnight. “Our
ground facilities and, as I understand, those abroad too did not
monitor this celestial body,” the
agency spokesman said.
Astronomers
around the globe didn’t notice the object coming either, and rushed
in search of its traces on satellite images after the news spread.
“Objects
like that are nearly impossible to see until a day or two before
impact,” Timothy
Spahr of the Minor Planet Center in Cambridge, Massachusetts told
Nature Magazine.
Although
the meteor was relatively small to detect, some argued its blast was
comparable with the power of a nuclear bomb.
According
to Canadian astronomer Margaret Campbell-Brown, the blast could be
even more powerful than North Korea’s recent nuclear test. Citing
the data from two infrasound stations near the impact site, she
estimated the object to be 15 meters in diameter with a mass of
around 40 tons.
“That
would make it the biggest object recorded to hit the Earth since
Tunguska,” Campbell-Brown
told Nature Magazine.
Most
scientists both in Russia and abroad do not believe the Chelyabinsk
bolide had anything to do with the asteroid 2012 DA14, which is
expected to fly by just hours
later
.
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