1. The objects that make up the Oort Cloud are too small and far away for WISE to see, but it will be able to track potentially dangerous comets and asteroids closer to home.

2. A Nasa graphic which illustrates how the Oort Cloud surrounds our solar system.

3. 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.

4. This is still well within the Oort cloud, whose boundary is estimated to be beyond 50,000 AU.

5. They start out in the Oort Cloud, a vast collection of perhaps trillions of small, icy chunks that hover at the very outer edges of the Solar System.

6. There it causes havoc in the Oort Cloud, a huge region surrounding the solar system that contains billions of bits of cosmic rubble left over from the formation of planets.

7. 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.

8. Every so often a comet gets flung out of the Oort Cloud, a swarm of comets on the fringes of the solar system, and gets close enough to Earth for us to see it.

9. They suggest that during its orbit it would regularly enter the Oort cloud, jostling the orbits of many comets there and causing some to fall toward Earth.

10. Nemesis would have followed a highly elliptical orbit[], perturbing comets in the Oort Cloud roughly every 26 million years and sending a shower of comets toward the inner solar system.

11. I believe it is likely that this is because the Oort Cloud is being disturbed by a massive body that is throwing comets out of stable orbits, a small fraction of which could reach the Earth.

12. Tyche is the nickname given to a hypothesized gas giant planet located in the Solar System's Oort cloud.

13. The hypothetical planet—or companion of the Sun—would be located in the outer part of the Oort cloud.

14. Neither Kirkpatrick nor Wright think Nemesis is disrupting the Oort cloud and sending comets towards Earth, however.

15. Our solar system is surrounded by a vast collection of icy bodies called the Oort Cloud.

16. Normal comets fall into the inner regions of the solar system from icy reservoirs in the distant Kuiper belt and Oort cloud.

17. Kuiper Belt in addition to discrete disk ecliptic,() the sun circle and still hypothetical Oort cloud.

18. But it would play a big role in the way comets ' made their way' from their birth places in the planetary disc out to the Oort Cloud and on now they can return to the inner solar system.

19. Beyond the orbit of Neptune one finds the disk-shaped Kuiper belt, in which dwarf planet Pluto resides, and far beyond that is the giant, spherical Oort Cloud and the teardrop-shaped heliopause.

20. Long-period comets are thought to come from the nearly spherical Oort cloud even further out, which get slung inward by the gravitational pull of passing stars.

21. Lissauer and his colleagues have long suspected a planet-size object, sometimes called Tyche, could be hiding in the Oort Cloud.

22. Another object dubbed Sedna, which is about three-fourths the size of Pluto, might be the first dwarf planet discovered in the Oort cloud.

23. 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.