The Moon

Aim: Does the moon actually change shape?

Why does the moon have so many craters?Earth was hit by the impactors too but we have weather, water, erosion, plants, plate tectonics that changes our surface.The moon does not have an atmosphere or water so its surface stays the same.

This footprint made on July 21, 1969 is still there.

Lunar Motions

The apparent daily motion of the moon is from east to west.As the moon makes one revolution around the Earth, it also makes one rotation on its axis.This is why we always see the same side of the moon (the same side of the moon is always facing the Earth)

Moon Terms

Sidereal Month – It takes the moon 27 1/3 days to complete one revolution (orbit) around the Earth.

Synodic Month – The time required for the moon to complete a cycle of phases is 29 ½ days.

INTERESTING FACT:

The word month comes from moonth since people used celestial

observations for time.

Our closest neighbor in space…

What have you noticed about the moon over a monthly cycle?

The moon seems to change its shape!

It’s a Phase they go throughThe amount of lighted side we can see from earth varies as the moon revolves around us during one month in a cyclic pattern.

The moon is always half lit and half dark – every round object in space is!From Earth, we only see a portion of the lit side

Moon’s Rotation = Moon Revolution

Rotation Period = 27.3 days

Revolution Period = 27.3 days

Moon shows the same “face” to the Earth

Velocity = 360/27.3 days = 13 per day

Moon’s Positions (or “Phases”)

New moon – the entire lit portion of the moon is facing AWAY from the earth; no light visible

Full moon – the entire lit portion of the moon is facing TOWARD the earth

Waxing: the RIGHT portion of the moon seems to GROW.

Waning: the LEFT portion of the moon seems to SHRINK

Waxing vs. Waning

Waxing phases are when the amount of lighted side we see increases each night

First light on right – from new to full

Waning phases are when the amount of lighted side we see decreases each night

Last light left – from full to new

Crescent vs. GibbousCrescent Moons – phases where you can see less than half of the bright side

Gibbous Moons – phases where you can see more than half of the bright side

Phases of the Moon

Sunlight

(1) New Moon

(2) Waxing Crescent

(3) First Quarter

(4) Waxing Gibbous

(5) Full Moon

(6) Waning Gibbous

(7) Third Quarter

(8) Waning Crescent

Earth

The general locations and

orientations for the phases of

the moon.

Earth spins on its axis in the

same direction as the moon’s

orbit.

Sunlight Earth

(1) New Moon

How much of the moon’s face does the

person see?

What time of day is it for the observer?

NEW MOON Wherever the

person looks all they see is

shadowed moon.

What part of the moon will we see?

Noon!!

More phases

Sunlight Earth

(2) Waxing Crescent

How much of the moon’s face does the

person see?

What time of day is it for the

observer?

WAXING CRESCENT When you look up

you see only a small crescent

brightly lit. (Right Side)

3PM!!

The next phase…

Sunlight

Earth

(3) First Quarter

How much of the moon’s face does the

person see?

What time of day is it for the observer?

FIRST QUARTER When you look up you see one half of

the front face of the Moon brightly

lit. (Right side)

Sunset - 6PM!!

And the next phase…

Sunlight Earth

(4) Waxing Gibbous

How much of the moon’s face does the person see?

What time of day is it for the observer?

WAXING GIBBOUS When you look up

you see only a small crescent, darkly

shadowed, on the left.

9PM!!

It’s becoming clear…

Sunlight

Earth(5) Full Moon

How much of the moon’s face does the person see?

What time of day is it for the observer?

FULL MOON When you look up you see the entire face of

the Moon brightly lit.

Midnight-12AM!!

Hey, what’s happening…

Sunlight

Earth

(6) Waning Gibbous

How much of the moon’s face does the

person see?

What time of day is it for the observer?

WANING GIBBOUS When you look up

you see only a small crescent,

darkly shadowed, on the right.

3AM!!

I’m melting…I mean shrinking…

Sunlight

Earth

(7) Third Quarter

How much of the moon’s face does the person see?

THIRD QUARTER When you look up you see one half of

the front face of the Moon brightly

lit. (Left side)

What time of day is it for the observer?

Sunrise - 6AM!!

Soon I’ll be gone…

Sunlight

Earth

(8) Waning

Crescent

How much of the moon’s face does the

person see?

WANING CRESCENT When you look up

you see only a small crescent

brightly lit. (Left Side)

What time of day is it for the observer?

9AM!!

Aim: How does the movement of our moon affect us?

Eclipse – blocked from view

What types of Eclipses are there?Solar Eclipses – the sun is blocked from view

The moon gets between sun and earthThe sun’s light is completely blocked by the moonCan only happen during new moon phase

but not every time, because moon’s orbit is tilted

Solar Eclipse Animation

Solar Eclipse Animation

Partial Eclipse Animation

The next total solar eclipse in New York will be 8/21/2017Mark your calendars now!!!

Lunar Eclipses – the moon is blocked from view

Occurs when full moon passes into Earth’s shadow and is temporarily blocked from view.

Sunlight is bent around Earth through our atmosphere. Mainly red light reaches the moon, so the totally eclipsed moon appears to have a reddish color.

How often do we have eclipses?

About 7 eclipses during every yearThe orbit of the moon is not in the same plane as the orbit of Earth around the sunThe moon’s orbit is tilted 5° to Earth’s orbitThis is why we do not have total eclipses so frequently

Moon may appear larger when closer

Moon’s Effect on Tides

Gravitational attraction pulls on Earth’s water creating a cycle of high and low tides

Spring TidesDuring the new moon and the full moonEarth, the sun, and the moon are alignedThe combined gravitational pull of the sun and the moon results in higher high tides and lower low tidesThe daily tidal range is greatest during the new and full moon periods

Neap TidesDuring the first-quarter moon and third-quarter moonEarth, the sun, and the moon are at right anglesThe combined gravitational pull of the sun and the moon work against each otherThe daily tidal range is small during this period

Two high tides and Two low tides

Every day cycle because earth rotates into and out of high water

Cycle of tides

Spring TideNOT the Season !!!Highest high tide when sun-earth-moon alignedDuring full and new moon positions only

Neap TideLowest high tide when sun-earth-moon at right anglesDuring quarter phases only