2018年IAO理论低年组第5题-奥尔特云

原文题目

Oort cloud. It is currently considered that tha source of long-periodic and non-periodic comets is th outer Oort cloud, the inner and ouyer radii of which are estimated as 0.2 and 0.8 light years, respectively. Comet bodies in this cloud move erratically and sometimes collide with each other. As a result, every century, people of the Earth observe from 10 to 20 bright comets coming into the internal regions of the Solar System. The average sizn of the nuclei of such comets is about 2-3kilometers. Roughly estimate (in order of magnitude) the total number of such comet bodies in the outer Oort cloud, the average distance between them, and their total maww. Compare the results with distance and masses of bidies in our Solar System.