1. Chapter 28: The Moon

2. Moons Are Natural Satellites
Satellite – a body that orbits another body
7 planets in our solar system have smaller orbiting bodies
Artificial satellites – satellites of Earth
Space telescopes
Weather data equipment

3. Moon Vocabulary – Mare (Maria)
Latin for “sea”
Large dark area of basalt on the moon
Dark solidified lava
Formed more than 3 billion years ago

4. Moon Vocabulary - Craters
Bowl-shaped depressions
Cover surface of moon
Formed from leftover debris during solar system’s formation

5. Moon Vocab – Ridges and Rilles
Long deep channels that run through maria
Ridges
Long narrow elevations of rock
Rise out of surface
Criss-cross maria

6. Moon Vocab - Regolith Layer of gas and dust
Covers most of the lunar surface
Formed from crushing of lunar rocks by meteorites

7. Lunar Rocks Similar to Earth rocks Igneous rocks
Contains many of same elements
Igneous rocks
Rocks that form when magma cools

8. Sides of the Moon… Near Side Far Side Always faces Earth
Always faces away

9. Lunar Layers 3 layers Crust Mantle Core Outer layer Beneath crust
Thicker on Far Side
km thick
Mantle
Beneath crust
Made of silica, magnesium, iron
Core
Small, made of iron
Neither completely solid nor completely liquid
Why Moon has almost no gravitational field

10. How Was the Moon Formed? Giant Impact Hypothesis
Large Mars-sized object collided with Earth
Over 4 billion years ago
Chunks of Earth’s mantle ejected into orbit
Debris eventually clumped together to form the Moon

11. Differentiation of Lunar Interior
When Moon formed…
Surface was covered by ocean of molten rock
Over time:
Denser material moved to center  formed core
Less dense material cooled  formed crust

12. Meteorite Bombardment
Meteorites had hit the Moon over time
Bombardment decreased significantly 3 billion years ago
Stopped all geologic activity on Moon
Moon has looked the same since then

13. Other Minor Bodies Other satellites that orbit the Sun
Leftover debris from formation of solar system
Include
Asteroids
Meteoroids
Meteorites
Comets

14. Asteroids Fragments of rock and metal Largest of the minor bodies
Orbit the Sun in ellipses
Largest of the minor bodies
Known as “minor planets”
Largest asteroid in solar system: Ceres
Other examples:
Earth-grazers – pass within 2x distance to the Moon
Trojan asteroids
Located on either side of Jupiter

15. Meteoroids Called meteors when enter Earth’s atmosphere
Small pieces of rock or metal in space
Meters to millimeters in size

16. Meteorites Any part of a meteor that is left when it hits Earth
3 types:
Stony
Iron
Stony-Iron

17. Comets Bodies of rock, metals, gases, and ice 3 major parts of a comet
Orbit the Sun
Long period – orbit lasts longer than 100 years
Short period – orbit lasts shorter than 100 years
3 major parts of a comet
Nucleus  core
Coma  spherical cloud of gas and dust around core
Tail evaporating gas and dust
Faces away from Sun

18. Comets, Cont’d Originate in the Oort Cloud
Spherical cloud of gas and dust
Lies beyond Pluto’s orbit
Contains nuclei of billions of comets