Scientists have discovered that dinosaurs were wiped out by a massive asteroid, the size of the Isle of Wight, that smashed into Earth 20 times faster than a speeding bullet.

They say that the impact of the crash sent a huge flume of smoke and dust into the atmosphere and caused a series of earthquakes.

The crash, which happened 65 million years ago, wiped out half of all the species on the planet, scientists think.

Researchers have been arguing for years about what might have killed the dinosaurs, with some saying that Earth must have collided with another planet, while others thinking that acid rain was the reason for their extinction. After 20 years of debate, a study has finally found that an asteroid was definitely the cause of their extension.

Dr Joanna Morgan, a scientist at Imperial College London who helped to write the review, said: 'We now have great confidence that an asteroid was the cause of the extinction.

One of the reasons why she thinks this is because researchers have found a 65-million-year-old layer of iridium ­– a rare metal that is found in rocks. Iridium is common in asteroids and researchers think that the iridium they found has come from a collision.

The metal is extremely rare in the Earth's crust, but is common in asteroids and almost certainly came from a collision with a massive asteroid.

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