1. The Moon & Tides Chapters 22.2 & 16.2

2. Motions of the Earth-Moon System
Orbital period = about one month
The moon’s orbit is elliptical
It is tilted 5 degrees off of Earth’s orbital plane

3. Perigee: Moon is closest to Earth
Apogee: Moon is farthest from Earth
Average distance from Earth to
the moon = 384,000 km = 238,607 miles!

4. Phases of the Moon
phases: various shapes of the moon lighted by reflected sunlight
Brain Pop: Moon Phases

5. waxing: when the size of the visible portion of the moon is increasing
waning: when the size of the visible portion of the moon is decreasing

6. new moon: no lighted area of the moon is visible from the Earth
full moon: entire half of the side of the moon facing Earth is lit

7. crescent: less than half of the side facing the Earth is lit
gibbous: more than half of the side facing the Earth is lit

8. New moon
Waxing crescent
1st quarter
Waxing gibbous

9. Full moon
Waning gibbous
Waning crescent
3rd quarter

11. Lunar Motions
Synodic Month: The cycling of the moon through its phases (Apparent Motion)
29 1/2 days
Basis for the first Roman calendar
Siderial Month: The moon revolutionary period around the earth (Actual Motion)
27 1/3 days
Occurs because Earth
is revolving around the
sun at the same time as the
moon is revolving around
The Earth!

13. 27 1/3 days! Why does the same side of the moon always face us?
Because the moon rotates and revolves at the same speed:
27 1/3 days!

14. Eclipses when one planetary body passes through the shadow of another
Brain Pop:
Eclipse

15. solar eclipse: when the moon is directly between the Earth and the sun

17. lunar eclipse: when the Earth is directly between the moon and the sun

19. Eclipses don’t occur every month because the moons orbit is tilted with respect to the Earth’s orbit

20. Tides Daily changes in the elevation of the ocean surface
Brain Pop: Tides
Result from gravitational attraction between… Earth, Moon, & Sun

21.               
The earth has a uniform level of water all around it.
2 forces act on the water to produce tides…
                                          
The moon’s GRAVITY pulls on the earth, and the water bulges toward the moon.
                                          
Because the earth is spinning, there is a force pulling water in the opposite direction  INERTIA

22. The Result…
As the earth turns upon its own axis in about 24 hours, a point on the earth moves through areas with these different forces acting on it.

23. Spring Tide – tides have greatest tidal range because the gravity of the sun & moon are combined

24. Neap Tide – daily tidal range is lower than average because the gravity of the sun & moon counteract each other

25. Tidal Patterns Diurnal - One high tide & one low tide each day
                                     
Semidiurnal - Two high tides & Two low tides each day

26. Tidal Graphing
 One Day
Multiple Days 