Phases, Eclipses, & Tides The moon revolves around the Earth as the Earth

revolves around the sun.★ The positions of the moon, Earth, & the sun cause

the phases of the moon, eclipses, and tides.

Motions of the Moon:As the moon revolves around the Earth it

rotates on its own axis

The moon & Earth have synchronous rotation, meaning the same side of the moon always faces Earth.

The “far side” of the moon always faces away from Earth & is never seen.

Phases of the Moon: The moon does not produce its own light, instead it reflects the light from

the sun. The moon has 8 phases and goes through the whole set once a month, or

29.5 days. What Causes Phases?

★The phase of the moon you see depends on how much of the sunlit side of the moon faces Earth.

The Cycles of the Phases:From one full moon to the next it takes about 29.5

days.The 8 phases of the moon in order are: New Moon,

Waxing Crescent, First Quarter, Waxing Gibbous, Full Moon, Waning Gibbous, Third Quarter, Waning Crescent.

Eclipses★When the moon’s shadow hits Earth or Earth’s shadow hits

the moon, an eclipse occurs.There are 2 types of eclipses: solar (sun) eclipse & lunar

(moon) eclipse.The type of eclipse is named for what is being blocked from

Earth.

Total solar eclipse Total lunar eclipse

Solar EclipseThe umbra is the darkest and smallest part of the shadow &

is cone shaped (total darkness).The penumbra is the largest part of the shadow

(partial darkness).Total Solar Eclipse:

○ Only people in the umbra experience a total solar eclipse.

Partial Solar Eclipse:○ In the penumbra, people only see a partial eclipse; since

part of the sun is still visible, it is not safe to look directly at the eclipse.

Lunar Eclipse During a full moon the

Earth blocks the sun’s light from reaching the moon making the moon look dark from Earth.

Total Lunar Eclipse○ When the moon is in the Earth’s umbra, there is

a total lunar eclipsePartial Lunar Eclipse

○ The moon passes partly into the umbra of the Earth’s shadow.

The Tide CycleThe moon’s gravity pulls Earth’s water

toward itself and away from 2 opposite places, creating low tides.

All 4 tides rotate in a 25 hour cycle.

Spring & Neap TidesSpring tides occur twice a month, one at

full moon & one at new moon.The combined force of the sun & moons

gravity make a tide with the most intense

high & low tide. Neap tides happen 2 times a month, one at first

quarter moon & one at third quarter moon.The sun & Earth are at right angles and creates

tides with the least intense difference between high & low. (It’s like a tug-of-war between the moon and sun).