National Geographic : 2013 Jul
58 national geographic • month 2011 the sOlar systeM’s attIc during the early chaos of the solar system, jupiter is thought to have flung trillions of comets and perhaps a few planets into deep space. only lightly bound to the sun, they now form a spherical cloud, called the oort cloud, around the solar system we know. in this view from the cloud, the sun and its familiar retinue are a small, bright swirl, and an undiscovered planet looms in the foreground. A new telescope being developed in chile might reveal such planets. two-part cloud Long-period comets come from the oort cloud. Their orbits suggest that the cloud (seen here in cross section) is a spherical shell close to a light-year across, bisected by a doughnut. The rest of the solar system (red) lies in the doughnut hole.