Process of Science: Name a testable hypothesis of nebular theory that was shown to be false in observations of extrasolar planets. Must we throw out the theory and start from scratch, i.e

Question

, is the observation completely inconsistent with a nebular formation?

Answer 1

At face value, the nebular theory predicts that massive, gas rich planets should form far from the star beyond the snowline. However, astronomers have discovered a large number of large planets that orbit close to their stars ("hot Jupiters"). This is partially because they are easiest to find, but still their existence was surprising and requires that the nebular theory be discarded or modified. Because it explains so many other facts, astronomers have preferred to modify the theory and have invoked planetary migration as a means to move massive planets that formed far from the star to much closer in.