When astronomers began searching for extrasolar planets, they were surprised to discover Jupiter-sized planets much closer than 1 AU from their parent stars.Why is this surprising?
A) These planets must have formed at larger radii where temperatures were cooler and then migrated inward, which is thought to be a rare phenomenon.
B) Jupiter-sized, rocky planets were thought to be uncommon in other solar systems.
C) These planets must be the remnants of failed stars.
D) Earth-like planets must be rarer than Jupiter-sized planets in other solar systems.
E) Jupiter-sized planets so close to the star are common and difficult to explain in our Solar System.

Question

Quizplus · Accepted Answer

Astronomers were surprised because gas giants like Jupiter are expected to form in the cooler, outer regions of a solar system and then migrate inward, which was initially thought to be a rare occurrence.

When Astronomers Began Searching for Extrasolar Planets, They Were Surprised