Figure 24.3: Earth has a hydrosphere, lithosphere, atmosphere, and biosphere. ( 6 )that the same force that keeps the Moon in its orbit is the same force that causes objects on
Earth to fall to the ground.
Figure 24.4: The planets orbit the Sun in regular paths. ( 21 )Newton defined the Universal Law of Gravitation, which states that a force of attraction,
called gravity, exists between all objects in the universe (Figure24.5). The strength of
the gravitational force depends on how much mass the objects have and how far apart they
are from each other. The greater the objects’ mass, the greater the force of attraction; in
addition, the greater the distance between the objects, the smaller the force of attraction.