The Cycles of the Moon

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Slide 1

The Cycles of the Moon

The phases of the moon

The tides

Lunar eclipses

Solar eclipses

Slide 2

The Phases of the Moon

From Earth, we see different portions of the Moon’s surface lit by the sun, causing the phases of the Moon.

Slide 3

The Phases of the Moon

The Moon orbits Earth in a sidereal period of 27.32 days.

27.32 days

Earth

Moon

Fixed direction in space

Slide 4

Is the moon going to show the same lunar phase after one sidereal period?

Yes.

No, it will not have completed a full cycle of phases.

No, it will have completed more than a full cycle of phases.

Slide 5

The Phases of the Moon

The moon’s synodic period (to reach the same position relative to the sun) is 29.53 days (~ 1 month).

Fixed direction in space

Earth

Moon

Earth orbits around Sun => Direction toward Sun changes!

29.53 days

Slide 6

The moon orbits counterclockwise around Earth (viewed from the North). => It appears to move eastward against the background of the stars. => The waxing crescent is visible

in the morning sky.

in the evening sky.

the whole night, from sunset to sunrise.

only around midnight.

never.

Slide 7

The Phases of the Moon

New Moon → First Quarter → Full Moon

Evening Sky

Slide 8

The Phases of the Moon

Full Moon → Third Quarter → New Moon

Morning Sky

Waning

Slide 9

The Tides

The tides are caused by the difference of the Moon’s gravitational attraction on the water on Earth

Between the near side and the center of the Earth

Between the center and the far side of the Earth

→ 2 tidal maxima

→ 12-hour cycle

Slide 1

On the day of full moon, high tides occur …

around noon and 6 p.m.

around noon and midnight.

around 6 a.m. and 6 p.m.

around 6 p.m. and midnight.

Impossible to tell. The times of tides are not correlated with the phases of the moon.

Slide 11

Spring and Neap Tides