Gravity is a force that attracts objects toward each other. Isaac Newton mathematically described gravity and its universal effects in 1666. The heavier an object is and the closer it is to another object, the greater the gravitational force. Gravity keeps the atmosphere and objects on Earth's surface and causes orbits and cycles like tides. The moon's gravity pulls on Earth's oceans, creating high tides, but the sun's more distant gravity does not have as strong an effect.

1. Gravity

3. Gravity – a force that pulls objects
toward each other

4. Who discovered gravity?
In 1666, Isaac Newton first mathematically
described the force of gravity, creating
Newton’s laws of universal gravitation.

5. What Affects Gravity?
– weight of the object
• The heavier the object is, the greater is the
force of gravity on that object
– distance between two objects
• The closer an object is to another, the greater
is the force of gravity on that object

6. How Gravity Affects
People and Surroundings
• Gravity keeps things
from floating off into space
• Important cycles
and processes

7. • Objects in Space Revolve Around each other
because of Gravity
• Gravity causes the rise and fall of Tides
– Tides are the rise and fall of sea levels. It
happens because of the gravitational pull of the
sun and the moon towards the bodies of water
on Earth.

8. The Moon has gravity of its own, which pulls the
oceans (and us) towards it. The Moon’s gravitational pull on
us is much weaker than Earth’s, so we don’t really notice it,
but we can see the Moon’s effect on the liquid water of the
oceans. The oceans are pulled towards the Moon’s gravity
slightly, causing a bulge or high tide on the side of the
Earth closest to the Moon.

9. 1. Why doesn't the earth fall down?
2. Why is there no gravity in space?
3. Why does the moon's gravity cause
tides on earth but the sun's gravity
doesn't?