1. 28.2 Movement of the Moon
Std 1F: Know the evidence for the dramatic effects that asteroid impacts have had in shaping the surface of planets.
Objective 1: Describe the shape of the moon’s orbit around Earth.
Objective 2: Explain why eclipses occur.
Objective 3: Describe the appearance of four phases of the moon.
Objective 4: Explain how the movements of the moon affect tides on Earth.

2. The Moon’s Elliptical Orbit
Chapter 28
The Moon’s Elliptical Orbit
The moon’s orbit around Earth =ellipse
the distance between Earth and the moon varies
apogee -the point at which the satellite is farthest from Earth
moon is farthest from Earth
perigee - the point at which the satellite is closest to Earth
the moon is closest to Earth

3. The Earth-Moon System

4. Moonrise and Moonset
The moon appears to rise and set at Earth’s horizon because of Earth’s rotation on its axis.
The moon rises and sets 50 minutes later each night because
Earth’s rotation
Moon’s revolution.

5. Lunar Rotation
The moon’s revolution around Earth and its rotation on its axis take the same amount of time.
Observers on Earth always see the same side of the moon.
The part of the moon illuminated by sunlight changes as the moon orbits Earth.

6. Eclipses
Eclipse - an event in which the shadow of one celestial body falls on another
Bodies orbiting the sun cast long shadows into space.
Shadows cast by Earth and the moon have two parts:
Umbra- the inner, cone-shaped part of the shadow
Penumbra - outer part of the shadow

7. Total Solar Eclipses
Solar eclipse - the passing of the moon between Earth and the sun; during a solar eclipse, the shadow of the moon falls on Earth.
During a total solar eclipse
The sun’s light is completely blocked by the moon.
The umbra falls on the area of Earth that lies directly in line with the moon and the sun.

8. Partial Solar Eclipse
Outside the umbra, but within the penumbra, people see a partial solar eclipse.
The penumbra falls on the area that immediately surrounds the umbra.

9. Effects of Solar Eclipses
During a total solar eclipse
Sunlight that is not eclipsed by the moon shows the normally invisible outer layers of the sun’s atmosphere (diamond-ring effect)
If the moon is at or near apogee during a solar eclipse, the moon’s umbra does not reach Earth.
This causes an “annual eclipse” - a thin ring of sunlight is visible around the outer edge of the moon.

10. Lunar Eclipses
Lunar eclipse - the passing of the moon through Earth’s shadow at full moon
Lunar Eclipses video

11. A lunar eclipse - Earth is positioned between the moon and the sun
Earth’s shadow crosses the lighted half of the moon.

12. Partial lunar eclipse - When only part of the moon passes into Earth’s umbra
Penumbral eclipse - When the entire moon passes through Earth’s penumbra

13. Solar and Lunar Eclipses

14. Phases of the Moon
phase - the change in the illuminated area of one celestial body as seen from another,celestial body; phases of the moon are caused by the changing positions of Earth, the sun, and the moon
As the moon revolves around Earth
different amounts of the near side of the moon are lighted.
The shape of the visible part of the moon varies.
The varying shapes are called phases.

15. Waxing Phases of the Moon
Full moon- the entire near side of the moon is illuminated by the light of the sun.
Waxing-gibbous phase - When the lighted part of the moon’s near side is larger than a semicircle
1st-quarter phase -When a waxing moon becomes a semicircle,
Waxing-crescent phase - When a sliver of the moon’s near side is illuminated
Waxing - When the size of the lighted part of the moon is increasing
Waxing Phases of the Moon

16. Waning Phases of the Moon
New moon - no lighted area of the moon is visible from Earth.
Waning -When the lighted part of the near side of the moon appears to decrease in size
Last-quarter phase - When the moon is waning, and it is a semicircle
Waning-gibbous phase- when the moon is waning, but is still larger than a semicircle
Waning-crescent phase - When only a sliver of the near side is visible

17. Phases of the Moon

18. Tides on Earth
Tidal bulges (Bulges in Earth’s oceans) - form because the moon’s gravitational pull on Earth decreases with distance from the moon
the ocean on Earth’s near side is pulled toward the moon with the greatest force
Because Earth rotates, tides occur in a regular rhythm at any given point on Earth’s surface each day.

19. Causes of Tides