Section 4: Earth’s Moon

What are we learning about today? 1. What features are found on the moon’s surface? 2. What are some characteristics of the moon? 3. How did the moon form?

Discover Activity: Why do Craters Look Different From Each Other? The moon’s surface has pits in it called craters. 1. Fill a large plastic basin to a depth of 2cm with sand. 2. Drop marbles of different masses from about 20 cm high. Take the marbles out and view the craters they created. 3. Predict what will happen if you drop marbles from a higher point. Smooth out the sand. Now drop marbles of different masses from about 50 cm high. 4. Take the marbles out and view the craters they left. Think it over In which step do you think the marbles were moving faster when they hit the sand? If objects hitting the moon caused craters, how did the speeds of the objects affect the sizes of the craters? How did the masses of the objects affect the sizes of the craters.

Earth’s Moon A. Telescope- a device built to observe distant objects by making them appear closer. 1. Galileo- 1 st to observe the moon using a telescope a. Observed that the moon was not smooth

I. The Moon’s Surface: Features on the moon’s surface include maria, craters, and highlands. A. Maria- the moon’s dark flat areas on the surface 1. maria is Latin for “seas” 2. are hardened rock formed from huge lava flows that occurred 3-4 billion years ago

B. Craters- large round pits on the moon’s surface 1. caused by meteoroids- chunks of rock or dust from space. 2. most formed from impacts early in its history before the maria formed 3. no atmosphere on the moon = very little change of the surface for billions of years.

C. Highlands- the light colored features on the moon’s surface 1. cover much of the moon’s surface 2. very rugged II. Characteristics of the Moon The moon is dry and airless. Comparted to Earth, the moon is small and has large variations in its surface temperature. A. Size and Density: 1. Is 3,476 Km in diameter a. ¼ of the Earth’s diameter 2. has less mass than the Earth 3. density is similar to the Earth’s outer layers.

B. Temperature and Atmosphere- 1. day 180 degree C 2. night -180 degree C 3. has no atmosphere, so temp’s widely vary 4. gases escape the surface bc gravity is so weak C. Water- 1. has no liquid water 2. evidence that ice is at the poles 3. temp’s so cold that ice never melts

III. The Origin of the Moon- A. Collision-ring theory- (pg. 33, figure 21) Scientists theorize that a planet-sized object collided with Earth to form the moon. 1. material from the object and Earth’s outer layers was ejected into orbit around Earth a. It formed a ring b. Gravity caused this material to form a moon