1. The Moon Distance from Earth ~235,000 miles
Diameter ~2,200 miles or ¼ Earth’s diameter
Daytime temp ~250F
Nighttime temp ~ -250F
No atmosphere
Reduced gravity – 1/6 Earth’s
No water, except maybe some ice in craters at poles

2. Moon’s Revolution & Rotation
Revolves around the Earth every 27.3 days
Rotates on its axis once every 27.3 days (synchronous rotation)
Same side always faces the Earth

3. Moon's Revolution and Phases

4. Moon’s Origin
About 4.5 billion years ago, a Mars-sized planetoid collides with the infant Earth.
Material from the collision blasted into orbit forms the Moon.
Called the Collisional Ejection or Giant Impact Theory

5. Moon’s Origin - Evidence
Isotopes of oxygen in moon rocks exactly match Earth rocks (formed from same material)
Moon’s iron deficiency – iron core of impactor merged with Earth’s core
Moon rocks lack volatile compounds – indicate the Moon’s surface was entirely molten
No other theory is as good

6. Highlands Light colored areas are the highlands cratered, mountainous
solidified about 4 billion years ago.

7. Maria
Dark-colored areas are the maria, smooth, few craters, solidified about 3 – 3.3 billion years ago.
Impact basins

8. On-Going Cratering
Rocks and comets collide with the Moon, vaporizing on impact.
Expanding gases blast out a crater.
Central peak forms where rock rebounds from explosion

9. The Far Side of the Moon Mostly Highlands
Craters mostly given Russian names, since USSR first photographed the far side in 1959.
Sorry Pink Floyd – the is no permanently Dark Side of the Moon – all parts of the Moon receive sunlight, except perhaps crater floors near the poles.

10. Near Side Far Side

11. Tides Mostly due to Moon’s gravitational pull on Earth’s oceans
Inertia produces high tide on Earth opposite the Moon
Ideally, there are 2 high and 2 low tides every 24 hrs 50 min
the Sun also plays a role, though not as significant as the moon

12. Neap Tides Occur when Sun, Earth, and Moon are at right angles
1st and 3rd Quarter Phases
Sun and Moon work against each other
Lower HIGH tides, and higher LOW tides.

13. Spring Tides Sun and Moon work together Higher HIGH tides
Lower LOW tides
Full and New Phases

14. Effects of Tides
The days are getting longer – s longer every 100 years
About 65,000,000 years ago, when dinos were last roaming the Earth, a day was only about 21 hrs and 15 minutes long!
The Moon is getting farther from the Earth ~ 3 cm/yr

15. The END