Earth’s Moon

Section 19.4

Surface of the Moon

• Maria – dark, flat areas of rock formed from lava flows

• Galileo thought they were oceans

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

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

Characteristics of the Moon

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

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