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.

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