You're reading: Sky fall: Meteorites strike Earth every few months

BERLIN — A meteor exploded in the sky above Russia on Friday, causing a shockwave that blew out windows injuring hundreds of people and sending fragments falling 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 30,000
kilometers an hour (18,642 mph) 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.

What caused the damage in Russia?

Alan
Harris, a senior scientist at the German Aerospace Center in Berlin,
said most of the damage would have been caused by the explosion of the
meteor as it broke up in the atmosphere. The explosion caused a
shockwave that sent windows and loose objects flying through the air in a
radius of several kilometers. By the time the remaining fragments hit
the ground they would have been too small to cause significant damage
far from the site of impact, he said.

Is there any link to the asteroid fly-by taking place later Friday?

No,
it’s just cosmic coincidence, according to European Space Agency
spokesman 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. 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. According to that theory, the
impact would have thrown up vast amounts of dust that blanketed the sky
for decades and altered the climate on Earth.

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 ($670) 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. Harris, of the German Aerospace
Center, says some meteorites are also believed to carry organic material
and may have influenced the development of life on Earth.

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 spokesman, says experts
from Europe, the United States and Russia are
already discussing how to spot potential threats sooner and avert them.
But don’t expect a Hollywood style mission to fly a nuclear bomb into
space and blow up the asteroid.

“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.”