1. Earth’s Moon Chapter 20 Lesson 2

2. Facts 1.2% less than Earth’s mass 1.2% less than Earth’s mass 27% less than Earth’s diameter 27% less than Earth’s diameter 384,000 km from Earth 384,000 km from Earth Rotation: 27.3 days Rotation: 27.3 days Revolution around Earth: 27.3 days Revolution around Earth: 27.3 days Reflects light from the Sun Reflects light from the Sun Formed with Earth around 4.6 billion years ago Formed with Earth around 4.6 billion years ago No atmosphere No atmosphere No liquid water No liquid water No plate tectonics No plate tectonics

3. Surface Features Craters Craters Objects crashed into surface Objects crashed into surface Rays – light-colored streaks extend outward Rays – light-colored streaks extend outward Most occurred 3.5 billion years ago Most occurred 3.5 billion years ago Maria Maria Large, dark, flat areas Large, dark, flat areas Formed from lava that flowed up through the Moon’s crust and solidified Formed from lava that flowed up through the Moon’s crust and solidified

4. Surface Features continued Highlands Highlands Light-colored areas too high for lava to cover Light-colored areas too high for lava to cover Figure 10 on p. 737 Figure 10 on p. 737

5. The Moon’s Motion Earth’s gravity pulls on the Moon and makes the Moon orbit Earth Earth’s gravity pulls on the Moon and makes the Moon orbit Earth One revolution around Earth = 27.3 days One revolution around Earth = 27.3 days Rotates as it revolves Rotates as it revolves One rotation = 27.3 days One rotation = 27.3 days The same side of the Moon always faces Earth (near side) The same side of the Moon always faces Earth (near side) The same side of the Moon always faces away from Earth (far side) The same side of the Moon always faces away from Earth (far side)

6. The Moon’s Motion

7. Phases of the Moon Caused by the motion of the Moon around Earth Caused by the motion of the Moon around Earth Called the lunar cycle Called the lunar cycle Lunar cycle = 29.5 days (slightly more than 4 weeks) Lunar cycle = 29.5 days (slightly more than 4 weeks)

8. Waxing Phases More of Moon’s near side is lit each night More of Moon’s near side is lit each night Week 1 – First Quarter Week 1 – First Quarter A sliver of light seen on Moon’s western edge A sliver of light seen on Moon’s western edge This sliver becomes larger throughout the week This sliver becomes larger throughout the week End of week: First Quarter End of week: First Quarter Entire western half is lit Entire western half is lit

9. Waxing Phases continued Week 2 – Full Moon Week 2 – Full Moon More and more of near side is lit More and more of near side is lit Full moon: near side is fully lit Full moon: near side is fully lit

10. Waning Phases Less of the Moon’s near side is lit each night Less of the Moon’s near side is lit each night Week 3 – Third/Last Quarter Week 3 – Third/Last Quarter Lit part becomes smaller and smaller Lit part becomes smaller and smaller Week 4 – New Moon Week 4 – New Moon Less and less of near side is lit Less and less of near side is lit New Moon phase: near side is completely dark New Moon phase: near side is completely dark

11. The Lunar Cycle

12. The Moon at Midnight Page 739 Page 739 First quarter First quarter Sets at midnight Sets at midnight Rises at noon Rises at noon Full moon Full moon Highest in sky around midnight Highest in sky around midnight Rises at sunset, sets at sunrise Rises at sunset, sets at sunrise Third quarter Third quarter Rises at midnight Rises at midnight