A 2021 study by Siraj and Loeb used the discovery of Borisov to infer that the majority of objects in this region are ISOs. This is the more distant of two regions that were meant to be observed by the proposed Whipple mission. To explain why this region would not have dissipated, an inner portion of it was proposed by and named for Jack G. Hills. The galactic (10[1])tide strongly perturbs objects in this region. (10[1])A discredited theory posited that a red or brown dwarf from this region named Nemesis was responsible for mass extinctions on Earth. Sedna may be from this region, whose spherical shape is suggested by the random orbital inclinations of the long-period comets (10[1])that originate from it. For 10 points, the outer boundary of the Solar System is defined by what hypothetical region named for a Dutch astronomer? ■END■