Section 4 – pg 488 Earth’s Moon Chapter 12 Section 4 – pg 488 Earth’s Moon

In 1609, the Italian scientist Galileo heard about a telescope and decided to build his own He saw that the moon has a irregular surface with a variety of remarkable features Pg 488

Pg 489 The Moon’s Surface Features on the moon’s surface include maria, craters, and highlands

Maria Maria: the moon’s surface has dark flat areas Pg 489 Galileo thought these were oceans Actually are hardened rock formed from huge lava flows that occurred between 3 and 4 billion years ago

Craters Craters: large round pits Pg 489 Caused by the impacts of meteoroids (chunks of rock or dust from space) The moon’s craters formed before the maria formed These formations have not changed because the moon has no water or wind to wear them down

Pg 489 Highlands Some of the light-colored features are highlands, or mountains

Characteristics of the Moon Pg 490 Characteristics of the Moon The moon is dry and airless Compared to Earth, the moon is small and has large variations in its surface temperature

Size and Density The moon is 3,476 km in diameter Pg 490 Size and Density The moon is 3,476 km in diameter This is a little less than the distance across the United States and a quarter the diameter of Earth The moon’s density is similar to Earth’s outer layer

Temperature and Atmosphere Pg 490 Temperature and Atmosphere On the moon’s surface, temperatures range from a torrid 130oC in direct sunlight to a frigid -180oC at night Temps vary so much because there is no atmosphere The moon’s gravity is too weak to keep gases from escaping into space

Water The moon has no liquid water Pg 490 Water The moon has no liquid water However, there is evidence that there may be large patches of ice near the moon’s poles

The Origin of the Moon Pg 491 Collision-Ring Theory Scientists theorize that a planet-sized object collided with Earth to form the moon Material from the object and Earth’s outer layers was ejected into orbit around Earth, where it formed a ring Gravity caused this material to combine to form the moon

Chapter 12 Section 4 Homework - Pg 491

1A. Name three major features of the moon’s surface.

1B. How did the moon’s craters form?

1C. Why is the moon’s surface much more heavily cratered than Earth’s surface?

2A. Describe the range of temperatures on the moon

2B. Compare Earth and the moon in terms of size and surface gravity

2C. What is the relationship between the moon’s surface gravity, lack of an atmosphere, temperature range?

3A. What theory best describes the moon’s origin?

3B. What was the solar system like when the moon formed?

3C. Explain the various stages in the formation of the moon