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.

Question

Quizplus · Accepted Answer

Jupiter-sized planets are thought to be formed beyond the snow line where temperatures are cool enough for gas and dust to clump together, leading to the planet's formation. Being closer than 1 AU from their parent stars would require them to migrate inward towards their parent star, which was not predicted by previous theories.

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