A massive dark object may be lurking on the edge of our solar system, according to scientists.
Most comets that fly into the inner solar system seem to come from the outer region of the Oort cloud - a region of icy dust and debris left over from the birth of the solar system.
The cloud starts from a point about 93 billion miles from the Sun and stretches for around three light years and contains billions of comets, most of them small and hidden.
A Nasa graphic which illustrates how the Oort Cloud surrounds our solar system. Scientists believe that an object with a huge mass may be pushing comets towards Earth from the cloud
Now new calculations suggest a large object that is up to four times as big as Jupiter could be responsible for sending them in our direction.
The scientists have analysed the comets in the Oort cloud and deduced that 25 per-cent of them would need a nudge by a body of at least Jupiter size before they changed orbit....MORE