Think about the twirling ball and string example as it relates to the solar system when considering:
Know the name of the path of the ball as it twirls around.
Knowing the name for the pull on the ball
Be able to describe the path of the ball if it was let go in space (you can talk about the 2 things that could happen as well)
Know:
How asteroids and comets are different
How asteroids and comets are similar
The two elements that make the main components of the sun
What gravity prevents the Earth from doing
The name of the star closest to Earth
The characteristics that Jupiter, Saturn, Uranus and Neptune share in common (There are 4: made of gas, past the asteroid belt, no surface to land on, and bigger than terrestrial planets)