When Astronomers Began Searching for Extra-Solar Planets,they Were Surprised to Discover

Multiple Choice

When astronomers began searching for extra-solar 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 radius where temperatures were cooler and then migrated inward.
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.