1. Chapter 23: The Sun-Earth-Moon System
Aim: What are Earth’s physical properties?

2. Physical Properties of Earth
Spherical shape
Rotates on an axis
Rotation of Earth:
causes day and night
1rotation= 1 day
Magnetic field
North and south pole
Protects you from harmful solar radiation by trapping charged particles from the Sun

3. Magnetic axis is different from its rotational axis
Magnetic axis-the line joining the north and south poles
When you follow a compass you are following the magnetic axis not rotational axis

4. Aim: What causes the seasons to change?

5. Orbiting the Sun 1revolution=1year Earth’s orbit is an ellipse
Distance from the Earth to the sun changes
Earth is closest to the sun in January
Earth is farthest from the Sun in July

6. Earth’s tilted axis causes seasons
2. A Titled Axis
Earth’s tilted axis causes seasons
The number of daylight hours is greater for the hemisphere that is tilted towards the Sun
Winter-hemisphere titled away from the Sun
Less sunlight each day
Summer-hemisphere titled towards the sun
Longer periods of sunlight each day

7. the Sun’s radiation strikes at a higher angle causing it to be hot
Earth’s tilt also causes the Sun’s radiation to hit the Earth at different angles
Summer
the Sun’s radiation strikes at a higher angle causing it to be hot
Winter
the hemisphere that is not tilted toward the sun, experiences less radiation

8. Solstices
The day when the Sun reaches its greatest distance north or south of the equator
Northern Hemisphere
Summer Solstice occurs on June 21 or 22
Longest day of the year
hours of sunlight begin to decrease
Winter Solstice occurs on December 21 or 22
Shortest day of the year
hours of sunlight begin to increase

9. Southern Hemisphere
Winter Solstice is in June
Summer Solstice is in December

10. Equinoxes Occurs when the Sun is directly above the equator
Causes fall and spring
#of daylight and night time hours are equal
Neither the Northern or Southern Hemisphere is tilted toward the Sun

11. Northern Hemisphere Southern Hemisphere Spring Equinox-March 20 or 21
Fall Equinox-September 22 or 23
Southern Hemisphere
Spring Equinox-September
Fall Equinox- March

12. Aim: How does the Moon move around the Earth?

13. The Moon Rotates on an axis Revolves around the Earth
Moons rotation and revolution both take 27.3 days
Because of this the same side of the moon always faces Earth
Moon’s surface reflects sunlight
Half of the moon is lighted, while the other half is dark

14. The moon’s appearance changes as the Moon revolves around the Earth and you see different portions of its lighted side

15. Aim: What are the phases of the Moon?

16. Phases of the Moon
Different forms that the moon takes in appearance from Earth
Phase depends on position of the moon, Earth and sun
New moon
Occurs when the moon is between the Earth and the sun
Lighted half of the moon is facing the Sun and dark side is facing the Earth
can not be seen
Rises and sets with the sun

17. Waxing Phases Begins after a new moon
Waxing-more of the illuminated half of the moon can be seen each night
Waxing crescent
24 hrs after a new moon you see a thin slice of the moon
First quarter phase
See ¼ of the moon’s surface
Waxing gibbous
More than ¼ of the moon is seen
Full moon
Occurs when all of the moon’s surface faces Earth

18. Waning Phases Happens after a full moon
You see less of the moon’s surface
Waning gibbous
begins just after a full moon
Third-quarter phase
See only half of the lighted side of the moon
Waning crescent
Occurs just before a new moon

19. Takes about 29.5 days for the moon to complete its cycle of phases
Discrepancy between cycle of phases and the moons revolution is due to Earth’s revolution

20. Aim: Why do lunar and solar eclipses occur?
Video

21. Causes of Eclipses Caused by the revolution of the moon
Occur when the Earth or moon block out the sun
Can only occur when the sun, Earth and moon are lined up perfectly
Solar eclipse happens during a new moon
Lunar eclipse happens during a full moon

22. Solar Eclipses
Occurs when the moon moves directly between the sun and the Earth
It casts a shadow over part of the Earth
Umbra-darkest part of the Moon’s shadow
Experience a total solar eclipse-can only see a pearly white glow around the edge
Penumbra-lighter shadow that surrounds the umbra
Experience a partial solar eclipse
Never look directly at the Sun, it can cause permanent eye damage

23. Lunar Eclipse Earth’s shadow falls on the Moon
Begins when the moon moves into the Earth’s penumbra
Curved shadow from Earth forms on the Moon
Total lunar eclipse-Moon completely in Earth’s umbra
Partial lunar eclipse-portion of the Moon moves into Earth’s umbra
Sunlight bent through Earth’s atmosphere-eclipse moon is red

24. Aim: How can features of the moon give us information about Earth?

25. Moon’s Surface craters-caused by meteorites, asteroids and comets
Dark, flat regions are called maria
Formed from lava
Igneous rock is 3-4 billion years old
Moon must have once been geologically active as Earth is today

26. Inside the Moon Use seismograph to study moonquakes
Has helped them draw models of moons interior
Figure 11 Pg 671

27. Origin of the Moon Apollo mission supported a new theory about Moon:
The Moon formed billions of years ago when Earth collided with a Mars-sized object
A ring of gas and debris formed around earth
Particles joined together to form the moon

28. Studying the moon has helped scientists draw conclusions about:
Earth’s shape
Movement of Earth and Moon around the Sun
Presence of surfaced features on bodies other than Earth

29. Aim: How have scientists studied the moon?
Students independently read Pgs They worked in pairs and threes to identify the Luna, Lunar Orbitors, Apollo and Clementine Mission.
Who launched it?
When it was launched?
Goal/objective of mission
Was it successful?