The Earth - Moon Cycle

1. The Earth - Moon Cycle By Ellis Clay

2. Science StandardsCalifornia Public Schools – Grade 3

3. Lesson Objectives • Students will learn about the origins, characteristics, and phases of the Moon, as well as its relationship to the Earth. • Students will examine the Earth-Moon relationship and determine the effects the Moon has on the Earth and how those effects influence the cycle of weather and tide • Students will draw conclusions from their examinations and speculate as to the potential consequences of a non-Moon system.

4. Investigation Questions • How was the Moon formed? • How old is the Moon? • Why does the Moon look different in the sky at different times of the month? • What is the relationship between the Earth and the Moon? • How does this relation-ship affect the Earth? • What would happen if the Earth had no Moon?

5. Origins of the Moon

6. Some facts about the Moon • According to the "giant impact" theory, the young Earth had no moon. At some point in Earth's early history, a rogue planet, larger than Mars, struck the Earth in a great, glancing blow. Instantly, most of the rogue body and a sizable chunk of Earth were vaporized. The cloud rose to above 13,700 miles altitude, where it condensed into innumerable solid particles that orbited the Earth as they aggregated into ever larger moonlets, which eventually combined to form the moon. • By measuring the ages of lunar rocks, we know that the moon is about 4.6 billion years old, or about the same age as Earth

7. More facts about the Moon • The distance between the Earth and its moon averages about 238,900 miles. The diameter of the moon is 2,160 miles. The moon's mass—the amount of material that makes up the moon—is about one-eightieth of the Earth's mass. • Because the force of gravity at the surface of an object is the result of the object's mass and size, the surface gravity of the moon is only one-sixth that of the Earth. The force gravity exerts on a person determines the person's weight. Even though your mass would be the same on Earth and the moon, if you weigh 132 pounds on Earth, you would weigh about 22 pounds on the moon

8. P h a sesofthe M oon

9. And more facts about the Moon • The rotation of the moon—the time it takes to spin once around on its own axis—takes the same amount of time as the moon takes to complete one orbit of the Earth, about 27.3 days. This means the moon's rotation is synchronized in a way that causes the moon to show the same face to the Earth at all times. One hemisphere always faces us, while the other always faces away. The lunar far side (aka the dark side) has been photographed only from spacecraft. • The shape of the moon appears to change in a repeating cycle when viewed from the Earth because the amount of illuminated moon we see varies, depending on the moon's position in relation to the Earth and the sun. We see the full moon when the sun is directly behind us, illuminating a full hemisphere of the moon when it is directly in front of us. The new moon, when the moon is darkened, occurs when the moon is almost directly between Earth and the sun—the sun's light illuminates only the far side of the moon (the side we can't see from Earth).

10. Still more facts about the Moon • The moon's gravitational pull on the Earth is the main cause of the rise and fall of ocean tides. The moon's gravitational pull causes two bulges of water on the Earth's oceans—one where ocean waters face the moon and the pull is strongest and one where ocean waters face away from the moon and the pull is weakest. Both bulges cause high tides. These are high tides. As the Earth rotates, the bulges move around it, one always facing the moon, the other directly opposite. The combined forces of gravity, the Earth's rotation, and other factors usually cause two high tides and two low tides each day. • To the unaided eye, the bright lunar highlands and the dark maria (Latin for "seas") make up the "man in the moon." A telescope shows that they consist of a great variety of round impact features—scars left by objects that struck the moon long ago. The largest scars are the impact basins, ranging up to about 1,500 miles across. The basins were flooded with lava some time after the titanic collisions that formed them. The dark lava flows are what the eye discerns as maria.

11. Summary & Conclusions The Moon is almost as old as the Earth. * The Moon has many phases. * The Moon affects the Earth in many ways. * Without the Moon, the Earth would be a very different place.