1. Earth’s Moon Section 19.4

2. Surface of the Moon Maria – dark, flat areas of rock formed from lava flows Galileo thought they were oceans

3. Surface of the Moon Craters – large, round pits caused by the impacts of meteoroids Scientists once thought they were volcanoes The absence of craters in maria indicates that the craters were formed early in the moon’s history

4. Surface of the Moon Highlands – mountains that cover much of the moon’s surface. The high peaks and crater rims cast dark shadows that we can see

5. Characteristics of the Moon 384,000 km from Earth (238,600 mi) 3,476 km in diameter (2160 mi) Dry and airless Temperature range = 130 o C to -180 o C Weak gravity (1/6 of Earth’s) No liquid water, but has ice at poles

6. Origin of the Moon (best explanation) Collision-ring Theory - A planet sized object collided with Earth - Material from the object and Earth’s outer layer was ejected into orbit to form a ring -Gravity caused this material to combine to form the moon