Moon and its motions

The Earth’s Moon

Surface features• Maria• Craters

Movements of the MoonLunar rotation and revolution

• Go to ESRT page 15

• Period of rotation = ______________

• Period of revolution = ______________

• https://www.youtube.com/watch?v=6jUpX7J7ySo&feature=em-subs_digest

• Why do we always see the same side of the moon?

27.3 days

27.3 days

Period of rotation = period of revolution

• To an observer on earth the moon rises and sets 50 min. later each night.

• Why is there a difference in period of revolution and the moon cycle?

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• Notice in picture 1, the moon is directly between the Earth and the Sun. But by position 5, even though the moon is directly below the Earth, it is no longer between the Earth and Sun. The moon must travel 2.2 more days to be exactly between the Earth and Sun (new moon).

• Time for moon to complete all phases in its cycle?29 - 30 days

• Apogee – farthest point in an orbit

• Perigee – closet point in an orbit

Moon’s Revolution

• Moon’s orbit around the earth is

• This causes the moon’s diameter/size to change in a

elliptical, with Earth at one of the foci

cyclic manner

Moon looks bigger at perigee,especially whenit first rises

Which is at perigee? Which is at apogee?

Perigee Apogee

Phases of the Moon - Reasons

• Caused by

• We see the illuminated part of the moon’s surface

• CYCLIC

Moon’s revolution around Earth

Phases of the Moon

Only the half facing the sun will be illuminated.

Color the illuminated and dark half of each moon.

Next, draw the moon’s orbit around the earth

Purple line is the orbit of the moon around the Earth

What does the moon look like from Earth at Position #1?

NEWMOON

What does the moon look like from Earth at Position #2?

WAXINGCRESCENT

What does the moon look like from Earth at Position #3?

FIRSTQUARTER

What does the moon look like from Earth at Position #4?

WAXINGGIBBOUS

What does the moon look like from Earth at Position #5?

FULLMOON

What does the moon look like from Earth at Position #6?

WANINGGIBBOUS

What does the moon look like from Earth at Position #7?

THIRDQUARTER

What does the moon look like from Earth at Position #8?

WANINGCRESCENT

Waxing and Waning

• Waxing – increase of moon’s visible light

• - new moon to full moon

• Waning – decrease of moon’s visible light

• - full moon to new moon

• Time is takes to go from full moon to the next full moon? ____________29-30 days

• http://apod.nasa.gov/apod/ap991108.html

• https://www.youtube.com/watch?v=79M2lSVZiY4

• (mr lee rap)