Meteorites strike Earth every few months
2013-02-15 14:35
Berlin - A meteor exploded in the sky above Russia on
Friday, injuring hundreds of people as its fragments fell to the ground in the
Ural Mountains.
Here's a look at those objects in the sky:
What's the difference between a meteor and a meteorite?
Meteors are pieces of space rock, usually from larger
comets or asteroids, which enter the Earth's atmosphere.
Many are burned up by the heat of the atmosphere, but
those that survive and strike the Earth are called meteorites.
They often hit the ground at tremendous speed - up to 30 000km/h
according to the European Space Agency. That releases a huge amount of force.
How common are meteorite strikes?
Experts say smaller strikes happen five to 10 times a
year. Large impacts such as the one Friday in Russia are rarer but still occur
about every five years, according to Addi Bischoff, a mineralogist at the
University of Muenster in Germany.
Most of these strikes happen in uninhabited areas where
they don't cause injuries to humans.
Is there any link to the asteroid fly-by taking place
later on Friday?
No, it's just cosmic coincidence, according to European
Space Agency spokesperson Bernhard Von Weyhe, who says Asteroid 2012DA14 is
unrelated to the meteorite strike in Russia.
When was the last comparable meteorite strike?
In 2008, astronomers spotted a meteor heading toward
Earth about 20 hours before it entered the atmosphere. It exploded over the
vast African nation of Sudan, causing no known injuries.
Largest strike
The largest known meteorite strike in recent times was
the "Tunguska event" that hit Russia in 1908. Even that strike, which
was far bigger than the one that happened over Russia on Friday, didn't injure
anyone. Scientists believe that an even larger meteorite strike may have been
responsible for the extinction of the dinosaurs about 66 million years ago.
What can scientists learn from Friday's strike?
Bischoff says scientists and treasure hunters are
probably already racing to find pieces of the meteorite.
Some meteorites can be very valuable, selling for up to
€500 per gram depending on their exact composition. Because meteors have
remained largely unchanged for billions of years - unlike rocks on Earth that
have been affected by erosion and volcanic outbreaks - scientists will study
the fragments to learn more about the origins of matter.
What would happen if a meteorite hit a major city?
Scientists hope never to find out, but they're still
trying to prepare for such an event.
Von Weyhe, the European space agency spokesperson, says
experts from Europe, the US and Russia are already discussing how to spot
potential threats sooner and avert them.
"It's a global challenge and we need to find a
solution together," he said. "But one thing's for sure, the Bruce
Willis Armageddon method won't work."
- AP
