1. Chapter 24.2 Earth’s Moon

2. Learning Targets
Explain how scientists think Moon formed
Describe the features of the Moon

3. Is the Moon the only place humans have visited?
Is Neil Armstrongs’s footprint still there? Why? No weathering!

4. Ideas on how the Moon was formed?

5. Formation of the Moon Giant Impact Hypothesis 4.5 billion years ago
Formed by impact of small planet with Earth
4.5 billion years ago
Planets collide  debris orbits Earth  eventually comes together to form Moon
Slowly moving away from Earth
Planet sized object from space collided with the Earth and sent trillions of tons of magma and rock into Earth’s orbit. Eventually, gravity pulled all of this material together to form the Moon.
How old is Earth? 4.5 billion years old

8. Earth’s Satellite Earth’s only natural satellite
Studied directly
Larger than any other moon of the inner planets
Last time we landed on the moon 1972

9. Satellite Any body that orbits a larger body
Mix of falling and moving forward results in round orbits

12. Lunar Characteristics
Moon’s Orbit
Rotates once every 27.3 days
Revolves around Earth every 27.3 days
No atmosphere
No weather  no weathering
Daily temperatures range from -243° to 225° F
The same side of the Moon always faces Earth. This means from Earth we always see the same side of the Moon.
Atmosphere moderates temperature. Since Moon has no temperature, greater variability in temperature.

13. Interior of the moon
Divided into layers like Earth: crust, mantle, core
No tectonic activity because the interior has cooled too much
Last volcanic activity ~ 1.2 billion yrs. Ago
No convection cells of molten rock  no plate tectonics
Because the Moon is not as dense as the Earth, gravity on the Moon is only one-sixth as strong as it is on Earth.
Material studied from the Moon’s surface is close in composition to the materials on Earth’s surface.

14. Like the Earth, the Moon has a distinct crust, mantle, and core
Like the Earth, the Moon has a distinct crust, mantle, and core. The crust is composed of igneous rock rich in the elements oxygen, silicon, magnesium, and aluminum.