Toll from meteor strike unprecedented
2013-02-15 16:00
Paris - A meteor strike in central Russia on Friday that
left hundreds of people injured is the biggest known human toll from a space
rock, a British expert said.
But the impact has no connection with a flyby by an
asteroid later on Friday, according to Robert Massey, deputy executive
secretary of Britain's Royal Astronomical Society (RAS).
"I am scratching my head to think of anything in
recorded history when that number of people have been indirectly injured by an
object like this... it's very, very rare to have human casualties."
Small space debris burns up harmlessly in the sky as it
enters the atmosphere, appearing in streaks of light called meteors that can
often be seen on a clear night, he said.
But, very rarely, larger objects survive the early stage
of descent before exploding in the lower atmosphere, causing a shockwave, which
is what happened on Friday, he said.
According to Russia's ministry of emergencies, almost 500
people were injured by flying glass as the windows were blown in.
Very much bigger objects - such as the rock that notoriously
ended the reign of the dinosaurs some 65 million years ago - can smash into the
Earth, delivering the energy of an arsenal of nuclear weapons, but these again
are even rarer.
Massey, basing his estimate on news reports, said on Friday's
object was in all probability less than 10m across before it collided with
Earth.
"It's unprecedented to have something like this
happen over an inhabited area and cause damage in this way," he said in a
phone interview from London.
"Events like this are not common - there were
several large falls in the 20th century, at least two of which were over
Siberia - but two-thirds of the Earth is ocean, so we tend to miss them."
Massey said there was no need for alarm over the event.
He stressed he saw "absolutely no connection"
between the event in the Chelyabinsk region and asteroid 2012 DA 14, which was
to skim the Earth on Friday at a distance of around 27 700km, the closest
known flyby by a space rock.
"It happened 12 hours earlier, and that amounts to
half a million kilometres of travel, [and] it seems to have been travelling in
a different direction - east-west, whereas the asteroid tonight will be
travelling south to north," said Massey.
