Why might it be difficult for Earth-like planets to form around Sun-like stars in the outer parts of the disk of our galaxy?

Question

Quizplus · Accepted Answer

The outer parts of the disk of our galaxy are where the metallicity (abundance of heavy elements) is lower, which makes it more difficult for rocky, Earth-like planets to form. This is because heavy elements are necessary for the formation of rocky planets. The lack of heavy elements makes it more likely for gas giants or ice giants to form instead.

Why Might It Be Difficult for Earth-Like Planets to Form