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The Meteor That Killed the Dinosaurs
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65 million years ago...
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The Earth was ruled by giants
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For 180 million years...
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...the dinosaurs ruled the planet.
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“Dinosaur” means “Terrible Lizard”
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T-Tex had no natural enemies.
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But suddenly, 65 million years ago, the dinosaurs and many other animals all died.
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Why did so many species die out...
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... so suddenly, leaving only fossils behind?
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Almost 50% of all life on Earth just died in a short space of time...
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... including the dinosaurs, the largest animals the Earth has ever seen.
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Some scientists think that giant volcanos were to blame.
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Perhaps the gases from a giant volcano poisoned the atmosphere?
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Others think that the climate changed and the dinosaurs died of cold or hunger.
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Most scientists though think that a visitor from space was to blame.
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There are many large rocks flying around in space.
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These are called “asteroids”
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The biggest is 940km across, but most are much smaller.
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Most asteroids orbit the Sun far away from the Earth between Mars and Jupiter, but a few can come close to the Earth.
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Most scientists think that 65 million years ago a big asteroid hit the Earth...
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The Moon is covered with many craters where asteroids have hit it.
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Others only a few centimetres across.
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Each was caused by an asteroid crashing into it.
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There are craters on the Earth too. The most famous one is in Arizona. It is 1km across.
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It is only a “small” crater compared to many on the Moon and was made by an asteroid perhaps 100-m across.
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From space you can hardly see it!
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...but the explosion was as bad as the biggest bomb ever exploded.
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The impact happened about 50 000 years ago.
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This crater in Canada is 100km across and was made when an asteroid 10km across hit the Earth 214 million years ago.
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Craters have been found all around the world, including in Spain.
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Some asteroids still hit the Earth
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The morning of June 30th 1908 a bright light was seen in the sky in Siberia.
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The light crossing the sky suddenly exploded. People 50km away were blown off their feet.
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The explosion destroyed the forest
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Trees were knocked over up to 15km away.
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Scientists estimate that the explosion may have been 1000 times bigger than the bomb that destroyed Hiroshima.
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The explosion was probably caused by a small asteroid, no more than 50-m across, hitting the Earth.
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Were the dinosaurs killed by the impact of an asteroid?
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For many years scientists looked for a crater that was 65 million years old
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But they were all either too old...
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Or too young!
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But, all around the world scientists have found evidence in the rocks that something strange had happened 65 million years ago.
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There is a layer of thin, grey rock, exactly 65 million years old.
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Younger rocks.
No dinosaur fossils.
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The grey rocks contain an metal called Iridium which is very rare on Earth, but more common in asteroids.
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It seems that a big asteroid hit the Earth 65 million years ago but, where is the crater?
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The answer is that it fell in the sea.
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The crater is hidden under the ocean.
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The asteroid fell in Yucatan in Mexico.
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An asteroid perhaps 20km across made a crater at least 180km in diameter .
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Special instruments can see the crater in the ocean floor.
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Measurements suggest that the crater may be 250km across in all.
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Dust and small pieces of rock thrown up by the explosion have been found all around the world.
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The impact would have caused a giant tsunami.
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Last Christmas we saw what a much smaller tsunami can do...
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Land and sea changed places...
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... and many people died.
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After the fire of the impact...
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...the tsunami changed the map of the world.
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Clouds and dust thrown up by the impact would have hidden the Sun for weeks or months.
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With no sunlight the weather became very cold...
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Could the same thing happen to us one day?
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Probably not, but...
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If it did, hundreds of millions of people might die...
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Perhaps it might happen like this...