Homework Assignment 1
 
 Prepare a short essay (no more than one page in length) explaining why the terrestrial planets (Mercury, Venus, Earth and Mars) are composed of dense, rocky material whereas the outer planets (Jupiter, Saturn, Uranus, Neptune and Pluto) are primarily composed of low-density, frozen gases of hydrogen and helium.  Do not hesistate to be creative in your explanation.  You should, however, make sure your explanation is consistent with the Nebular hypothesis for the origin of the solar system.