A comet striking Earth was behind the extinction of the dinosaurs.

Life on Earth is wiped out every 27 million years – and we have about 16 million years left until the next extinction, according to scientists.

Research into so-called ‘extinction events’ for our planet over the past 500 million years - twice as long as any previous studies - has proved that they crop up with metronomicregularity.

Scientists from the University of Kansas and the Smithsonian Institute in Washington DC are 99 per cent confident that there are extinctions every 27 million years.

In the 1980s scientists believed that Earth’s regular extinctions could be the result of a distant dark twin of the Sun, called Nemesis.

The theory was that Nemesis crashed through the Oort cloud every 27 million years and sent a shower of comets in our direction.

The Oort cloud is a vast belt of dust and ice that is believed to lie around one light year from the Sun and is the origin of many of the comets that pass through our solar system.

But now scientists claim that the regularity of the mass extinctions actually disproves the Nemesis theory because its orbit would have changed over time as it interacted with other stars.

‘Fossil data, which motivated the idea of Nemesis, now militateagainstit,’ say the researchers.

The last extinction event, 11 million years ago, saw 10 per cent of the Earth’s inhabitants wiped out.

This means there is around 16 million years until the next event takes place, although the graph shows that it occasionally the event takes place up to 10 million years early.

Asteroidscrashing into the Earth are commonly believed to be one of the main reasons behind mass extinctions like that suffered by the dinosaurs - the Cretaceous-Tertiary(KT) extinction.

The extinction wiped out more than half of all species on the planet clearing the way for mammals to become the dominant species on Earth.

The extinction was caused by a massive asteroid slamming into Earth at Chicxulub in Mexico.

The asteroid, which was around 15 kilometres wide, is believed to have hit Earth with a force one billion times more powerful than the atomic bomb at Hiroshima.