17.1

● Gravitational force

● Law of Universal Gravitation

● Orbit

● Axis

● Rotation

● Revolution

● Planet

● Solar System

● Satellite

18.1

● Circumference

● Mass

● Giant Impact Theory

● Crater

18.2

● Lunar Cycle

○ New moon

○ waxing crescent

○ first quarter

○ waxing gibbous

○ full moon

○ waning gibbous

○ last quarter

○ waning crescent

● Lunar Eclipse

● Solar Eclipse