1. Astronomy: Earth, Sun & Moon Overview & Objectives
Know about the Earth, Inside & Out
Interior, Plate Tectonics, Atmosphere, Magnetic Field
Know about the Moon: Earth’s Fellow Traveler
Size, Distance, Orbit, Composition, Origins
Know about the Sun
Size, Distance, Energy, Composition
Understand the Relationship b/w Earth, Sun, Moon
Eclipses, Seasons
Chapter 2, Lesson 1 & 2
Chapter 3, Lesson 1

2. Earth’s Interior
3 Layers:
Crust
Mantle
Core
Chapter 2, Lesson 1

3. Earth’s 3 Layers Crust - outer layer (only 60 miles thick)
Mantle – middle layer
1,800 miles thick (½ way to center)
Solid, but can flow slowly
Core – center
Denser than mantle (iron & nickel)
Liquid outer core
Solid inner core
Chapter 2, Lesson 1

4. Motion of the Earth’s Crust
Do the continents move?
Continental drift - gradual motion of the continents relative to one another
Why do they move?
Chapter 2, Lesson 1

5. Motion of the Earth’s Crust
Plate tectonics - motion of sections (plates) of Earth’s crust across the underlying mantle
But what causes the plates to move?

6. Plate Tectonics Convection of heat in Mantle Explains much of Earth’s
features & topography
Mountains
Volcanoes
Earthquakes
Ocean mountains/trenches
Rift zone - line near center of the oceans - lava flows upward
Mid Atlantic Ridge & Mid Oceanic Rise
Chapter 2, Lesson 2

7. Video

8. Plate Tectonics
Earthquake Locations
Chapter 2, Lesson 2

9. Earth’s Atmosphere Very thin onion skin (only 90 miles) 4 layers
Composition?
Mostly nitrogen & oxygen
All weather occurs in:
Troposphere (7-8 miles)
Ozone layer
Protects us from fatal ultraviolet (UV) radiation from Sun

10. Earth’s Magnetic Field
Caused by
Uses:
Compasses
Protects us from harmful sun rays
Magnetic poles shift each year (can flip!)
iron core

11. Earth’s Magnetic Field
Charged particles from Sun are captured by Earth’s magnetic field (Van Allen Belts)
Aurora (Northern & Southern Lights)
Light radiated from impacts of charged particles Video

12. Moon’s Size & Distance Diameters Earth – 7,800 miles
Moon – 2,160 miles
Comparison?
About ¼ size of Earth
Moon distance from Earth
240,000 miles
Activity
Chapter 2, Lesson 2

13. Moon’s Orbit Moon’s orbit is elliptical Appears larger at perigee
Closest distance
Appears smaller at apogee (farthest distance)
How long to orbit the Earth?
One “Moonth” (month)!
27.3 days
Why do you always see
same face of the Moon?
Rotates 1 time per orbit

14. Moon’s Orbit Phases Causes Tides on Earth: Full, New, Quarter Moons
Waxing & waning?
Causes Tides on Earth:
Moon’s gravity pulls on Earth causing “bulges” in oceans
Chapter 2, Lesson 2

15. Moon’s Composition Crust 62 miles thick Moonscape:
Maria (singular “Mare”)
“Seas” - Lunar lowlands
Impacts from meteorites that filled craters in w/ lava
Highlands
Mountains - result of millions of ancient craters piled up on top of one another

16. Moon’s Origin - 4 Theories
Double Planet Theory – Moon formed at same time as Earth
Fission Theory - material spun off from Earth
Capture Theory
Large Impact Theory
Large object impacted the Earth
Metal cores combined to form massive Earth core
Lighter material thrown off became the Moon
- space debris was captured by Earth
Chapter 2, Lesson 2

17. Size & Distance of the Sun
865,000 miles diameter
You could fit 1,000,000 Earths in the Sun!
93,000,000 miles from Earth!
Remember activity?
200 mi = 1”?
Sun = 360’
7.3 Miles away
8 mins at speed of light
Earth
Chapter 2, Lesson 2

18. Composition of the Sun “The FURNACE”
¾ of Sun is
Primary source of Sun’s energy:
Atom nucleus - protons & neutrons
Nuclear fusion – 2 nuclei “fuse” to form a larger nucleus
Incredible gravity at center of
Sun fuses protons = Heat source
Hydrogen, the rest is mostly Helium
nuclear fusion reactions

19. Sun’s Atmosphere 3 Main Layers: Photosphere Chromosphere
Region where solar flares erupt
Corona
- Outermost region
- Extends 100,000 miles
- visible part that emits light
- region b/w photosphere & corona

20. Sun’s Atmosphere “The Solar Wind”
Solar wind – a continuous outflow of charged particles
from the Sun
What protects Earth?
Its magnetic field & atmosphere
Flying out at 249 miles/sec!
Significant role in space weather activity
Causes Aurora Borealis
Chapter 3, Lesson 1

21. Sun Spots and Flares
Sunspots - dark spots appearing periodically in groups on surface
Effect on Earth?
Cooler climates
Solar Flares
Solar flares – a surface explosion
Ejected 1,000s of miles into space
Effect on Earth?
Can disrupt satellites & radio transmissions

22. Earth & Sun Relationship: Seasons
Why are there seasons? reasons:
Earth is “tilted”
Rotation
Video 1 Star Spin Video 2 Actual Spin
Earth orbits the Sun:
23.5°
24 hours (1 Day)
days (1 Year)

23. Earth & Sun Relationship: Seasons
Solstices
Summer & Winter
Sun farthest distance from the “celestial equator”
Longest & shortest days of the year
Equinoxes
Vernal (Spring)
Autumnal (Fall)
Sun crosses
“celestial equator”
Night/day are equal

24. Earth, Moon & Sun Solar Eclipses
Sun about 400x larger than the moon…
But Sun is about 400x farther away than the moon
So, they appear the EXACT SAME SIZE on Earth!!!
Certain times the Moon perfectly covers the Sun
Chapter 3, Lesson 1