Why do the outer giant planets have massive gaseous atmospheres of hydrogen and helium whereas the inner planets do not?
A) These gases were more abundant in the outer regions of the accretion disk where the outer planets formed.
B) The outer planets grew massive quickly enough to hold on to these gases through gravity before the solar wind dispersed the accretion disk.
C) The inner planets "used up" all of the rocky materials.
D) Frequent early collisions by comets with the inner planets caused most of their original atmospheres to dissipate.
E) They were most likely captured by the Sun after our Solar System formed.

Question

Quizplus · Accepted Answer

The outer planets grew massive quickly and were able to retain their gaseous atmospheres due to their strong gravitational pull, while the solar wind dispersed these gases from the less massive inner planets.

Why Do the Outer Giant Planets Have Massive Gaseous Atmospheres