The Oort cloud is a shell of icy objects that forms the very outskirts of our Solar System. Recently, a group of researchers discovered that the inner portion of the Oort cloud likely has spiral ...

Simpson's paper, "How might a planet between Mars and Jupiter influence the inner solar system? Effects on orbital motion, obliquity, and eccentricity," was published in Icarus, a journal devoted ...

The inner Oort cloud, between 1,000 and 10,000 AU from the sun, displays a spiral formation with arms that extend 15,000 AU.