How far away is the Oort comet cloud? 1000 AU or 10,000 AU? c=10^10 cm/sec. for 10^8 sec/yr., gives 10^18 cm/lyr. Approximately then, is 1000 AU ~ .01 lyr? And 10,000 AU ~ .1 lyr? Would this be large enough to contain a multi-stellar system, since stars form in multiple? Hence a common Oort cloud for a center of mass for such system?