Climate change, asteroids, super volcanos and now dislodged comets - the risk to planet Earth grows ever greater.
Scientists have identified a 26-million-year cycle of meteor impacts that coincides with the timing of mass extinctions over the past 260 million years.
They say the planet could be in danger as the Sun’s journey through the galaxy dislodges comets and sends them flying between the planets.
The doomsday events are linked to the motion of the Sun and its family of planets through the dense mid-plane of our galaxy, the Milky Way.
Gravitational disturbance of the Oort Cloud - a shell of icy objects on the outer edge of the solar system - is believed to lead to periodic showers of comets pouring through the inner region where the Earth resides.
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The last of these events is said to have occurred about 11 million years ago, roughly the same time as the Middle Miocene mass extinction.
But according to Professor Michael Rampino, a US geologist, it might be wrong to assume that we are living in a completely safe era, millions of years away from the next danger period.
He said: “There is evidence that the comet activity has been high for the last one to two million years, and some comet orbits are perturbed, so we may be in a shower at the present time.
“That would agree with our position near the galactic mid-plane, where perturbations from dark matter etc. would be expected.”
Dark matter is the mysterious invisible substance that surrounds galaxies and can only be detected from its gravitational effects. It is believed to account for more than 80 per cent of all the matter in the universe.
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Professor Rampino, from New York University, and Professor Ken Caldeira, from the Carnegie Institution, carried out an analysis of meteor impacts and extinctions using new data providing more accurate age estimates.
They found that six mass extinctions correlated with the timing of heightened periods of impact cratering on Earth.
One of the impacts studied was caused by the large comet or asteroid that struck the Earth 65 million years ago off the Yucatan coast of Mexico and is said to have wiped out the dinosaurs.
Five of the six largest impact craters coincided with mass extinction events, said the scientists writing in the journal Monthly Notices of the Royal Astronomical Society.
“The correlation between the formation of these impacts and extinction events over the past 260 million years is striking and suggests a cause-and-effect relationship,” said Professor Rampino.
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“This cosmic cycle of death and destruction has without a doubt affected the history of life on our planet.”