THE MOONTHE MOON

THE SURFACE OF THE MOON• It has no atmosphere, so a record of all

the impacts has been preserved• We know the age of the moon, so by

counting the # of impact craters they can find the rate of cratering.

• Knowing the rate of cratering, scientists can use the # of craters on any body to estimate how old the body’s surface is.

LUNAR ORIGINSLUNAR ORIGINS

• 3 popular explanations for the 3 popular explanations for the moon’s origins:moon’s origins:– 1. The moon was a separate body 1. The moon was a separate body

captured by Earth’s gravity.captured by Earth’s gravity.– 2. Moon formed at the same time & from 2. Moon formed at the same time & from

the same materials as the Earththe same materials as the Earth– 3. The newly formed Earth was spinning 3. The newly formed Earth was spinning

so fast that a piece flew off & became so fast that a piece flew off & became the moonthe moon

LUNAR ORIGINSLUNAR ORIGINS

• The composition of the Moon was similar The composition of the Moon was similar to the Earth’s mantle.to the Earth’s mantle.

• Found through rock samplesFound through rock samples

• Current Theory:Current Theory:– A large object collided with Earth, while the A large object collided with Earth, while the

Earth was still forming.Earth was still forming.– This was so violent that a chunk of the earth’s This was so violent that a chunk of the earth’s

mantle was blasted into orbit around the earth mantle was blasted into orbit around the earth to form the Moonto form the Moon

PHASES OF THE MOONPHASES OF THE MOON

Within a month it changes from a Within a month it changes from a fully lit circle to a thin crescent back fully lit circle to a thin crescent back to a circle.to a circle.

This is a result from its changing This is a result from its changing position relative to the earth and the position relative to the earth and the SunSun

As the moon revolves around the As the moon revolves around the Earth, the amount of sunlight on the Earth, the amount of sunlight on the side of the moon that faces the Earth side of the moon that faces the Earth changeschanges

PHASES OF THE MOON

• New Moon• Waxing

Crescent• First Quarter• Waxing Gibbous• Full Moon

• Waning Gibbous• Last Quarter• Waning

Crescent

• Moon is between the Sun and Earth and is not visible in the sky

• Lighted area appears to be growing larger

• Right side of the Moon as seen from Earth is lighted.

• ¼ OF THE WAY AROUND THE EARTH. HALF OF THE MOON IS LIGHTED

• Lighted areas of the moon continues to grow.

• Right side of the Moon as seen from Earth is lighted.

• Entire lighted side of the Moon is visible from Earth

• Lighted area of the Moon appears to be getting smaller.

• Left side of the Moon as seen from Earth is lighted.

• ¾ of the way around the Earth.

• Half of the moon is lighted.

• Lighted area continues to grow smaller.

• Left side of the Moon as seen from Earth is lighted.

Waxing and Waning

• WAXING– The sunlit fraction we can see is getting LARGER

• Waning-– The sunlit fraction we can see is getting

SMALLER• The moons period of rotation is the same its

period of revolution, so on Earth you always see the same side of the moon

How the Moon affects the Tides

ECLIPSESECLIPSES•Eclipse:

–When the shadow of one celestial body falls on another

SOLAR ECLIPSESOLAR ECLIPSE

– When the moon comes between the Earth and the Sun and the shadow of the moon falls on part of the Earth

– Annular eclipse (partial):• Moon is farther from the Earth• The disk of the moon does not completely cover the

disk of the Sun• Penumbra – lighter outer part of a shadow

– Total Solar Eclipse:• The disk of the moon completely covers the disk of

the sun• Umbra – Darker inner part of a shadow

Umbra & PenumbraUmbra & Penumbra

LUNAR ECLIPSELUNAR ECLIPSE

• Happens when the Earth comes between the sun and the moon and the shadow of Earth falls on the moon.

• During a lunar eclipse the Earth’s atmosphere acts like a lens and bends sunlight into the Earth’s shadow.

• Most of the light you see during a lunar eclipse is red.

The Tilted Orbit Of The MoonThe Tilted Orbit Of The Moon

►The Moon is tilted about 5 degrees The Moon is tilted about 5 degrees relative to the orbit of the Earth relative to the orbit of the Earth around the Sun.around the Sun.

►This is enough to place the moon out This is enough to place the moon out of the Earth’s shadow for most full of the Earth’s shadow for most full moons and the Earth out of the moon’s moons and the Earth out of the moon’s shadow for most new moonsshadow for most new moons

How the tilt affects the How the tilt affects the seasonsseasons

Seasons Seasons

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