1. Earth, Moon, and Sun
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2. Earth’s 2 Motions 2. Revolution (orbit) Rotation – go around the Sun
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Earth’s 2 Motions
2. Revolution (orbit)
– go around the Sun
Rotation
– Spin (rotate) on its axis

3. Rotation The turning of a planet on its axis Axis:
23.5 0
Axis
Axis:
Imaginary line that runs from the North Pole, through the center of Earth, to the South Pole.
Earth’s axis is tilted at
We have days and nights because of Earth rotating in and out of sunlight
Table of Planets day

4. Rotation
The direction of Earth’s rotation is counterclockwise (when looking from above the North Pole)
Because Earth rotates counterclockwise, it appears the Sun rises in the East and sets in the West

5. Rotation It takes Earth 24 hrs to complete one rotation
One complete rotation of any planet is called a Day
At the Equator, Earth rotates 1,000 mph
The faster a planet rotates, the shorter the day is on that planet
Cool Fact: Earth is slowing down at a rate of seconds per century

6. Revolution Movement of a planet around the Sun
Counterclockwise (from above NP)
One complete revolution of any planet around the Sun is called a year
Earth rotates 365 ¼ times during one revolution around the Sun (There are 365 ¼ days in a year)
We make up for that extra ¼ day by adding a day to our calendar (Feb 29th) every 4 years Leap Year

7. Revolution
The closer a planet is to the Sun, the shorter its year is , because:
It has to travel a shorter distance
Its speed is greater due to the Sun’s gravity
**Earth Revolves at an average of 67,000 mph

8. Revolution Orbit - The path a planet follows around the Sun
- Shape is elliptical (Oval) with the Sun off-center (not in the middle!)
95 million miles
91 million miles
Average= 93 million miles
Perihelion

9. 2 Forces that Keep Earth in Orbit:
Inertia
Body in motion will remain in motion
Body at rest will remain at rest
**Inertia is why the planets keep moving ( in a straight line)
Unless acted upon by an outside force
Gravity
The Sun’s gravity pull planets toward the Sun and keeps them in their orbital path

10. ~15hrs ~12 hrs ~9hrs ~12 hrs Equator Equator Tropic of Cancer
Tropic of Capricorn
Equator
~12 hrs

11. Why is there More Hrs of Daylight in Summer?
24 hrs darkness
24 hrs daylight
24 hrs daylight
24 hrs darkness
Why is there More Hrs of Daylight in Summer?

12. Seasons
The seasons in one hemisphere are opposite of the seasons in the other Hemisphere
**Seasons in the Southern Hemisphere are more extreme than in the Northern Hemisphere

13. Tropic of Capricorn (23.50 below Equator)
Tropic of Cancer (23.50 above Equator)
Northern Hemisphere
Equator
Southern Hemisphere
Bill Nye- seasons

14. Seasons Animations:
Video clip
Bill Nye Seasons
Video clip #2

15. The Moon Revolves around Earth ¼ Earth’s diameter (2,159 miles)
1/6 of Earth’s gravity
Frozen water ice at the poles (in deep shadowed craters)
Mainly rock and dust (brought back 840lbs of rock to Earth

16. The Moon NO atmosphere  therefore NO weather
Temp range is large since it lacks an atmosphere
250F = high during the day
-250F = low at night
Lots of craters from impacts because it lacks an atmosphere
Old and unchanged because it lacks an atmosphere

17. Our Moon Has 2 Motions: Rotation Revolution
counterclockwise
10.7 mph on its axis (6.70)
Takes 28 days to rotate once
Lunar Day = 28 Earth days
Revolution
Around Earth at 2,300 mph
Orbit is Tilted (5º)
Orbit is elliptical (Perigee and apogee)
Average distance to the moon is 238,000 miles
Lunar Year = 28 Earth days
A Day is as long as a Year on the Moon!

18. Why Don’t We See the Far Side?
The Moon rotates 1 time around its axis as it makes 1 revolution around Earth.
It finishes a rotation at the same time it finishes a revolution
Period of Rotation = Period of Revolution
28 Earth Days
Dark Side
FACT:
The Moon does not rotate and revolve at the same speed!

19. Phases of the Moon The Moon reflects sunlight
It does NOT produce its own light
We see different phases (shapes) depending on where the moon is in its orbit
It takes the Moon about 28 Earth days to complete one revolution around Earth and go through all of its phases

20. New Moon During a New Moon we can’t see the moon from Earth
The side hit by sunlight is facing AWAY from Earth
Occurs when the Moon passes between the Earth and Sun
Moon is above or below Earth’s plane 20

21. Full Moon
After a New Moon, the Moon continues to revolve in a counterclockwise direction allowing us to see more and more of the side facing us. (Waxing Phases)
When it gets halfway around Earth, we see ALL of the side facing us

22. Full Moon (cont.) Earth is between the Moon and Sun
Moon is above or below Earth’s plane
As the Moon continues to revolve from a full moon position, we see less and less of the side facing us (Waning Phases), until we have another New Moon

23. Animation
Animation

24. Eclipses Lunar Eclipse Solar Eclipse
Moon is being eclipsed (blocked from our sight)
Solar Eclipse
Sun is being eclipsed by the moon (blocked from our sight)
Moon is 400 x smaller than the Sun
Moon can perfectly block out sun because the moon is 400x closer to us than the sun is
FACTS:
Earth is 4x bigger than Moon
Sun is 100x bigger than Earth

25. Lunar Eclipse
Earth is directly between the Sun and a Full Moon (all 3 bodies are in line)
Moon is in the shadow of Earth (no sunlight hitting it)
Only happens 2-4 times a year (not all total)
Zone of partial shadow
Zone of complete shadow
Whole back side of Earth can see Lunar Eclipse

28. Solar Eclipse
When a New Moon is directly between the Earth and Sun (all 3 bodies are in line)
Sunlight is blocked (by the moon) from reaching a small area of Earth, so only people living in that area see the solar eclipse
At least 2 a year (not all total)
People in penumbra see partial solar
People in umbra see total solar

30. Tides Rising and falling water levels of our oceans
Moon’s and Sun’s gravity makes water bulge out on Earth
The Moon’s gravity has a greater effect because it’s closer than the Sun
The area aligned with the moon  High Tide
The area not aligned with the moon  Low Tide
Spring tides
Neap tides
Bill Nye- Moon