This lesson makes a nice counterpart to Lesson 4, Measuring G-Forces.
Gravity is a universal, natural force that attracts objects to each other.
Gravity is the pull toward the center of an object, such as the center of a planet or a moon. The Moon has a weaker gravitational attraction than Earth. Explain that the numbers in parentheses describe the amount of gravitational pull that planet has. Have students write down the names of all the listed planets. Pluto 0.01 Sun 28 5.