The Earth-Moon The Earth-Moon SystemSystem

SpheresSpheres

A sphere can be A sphere can be defined as a three defined as a three dimensional figure dimensional figure like a ball – The like a ball – The Sun, all planets and Sun, all planets and moons are spheresmoons are spheres

EllipseEllipse An An ellipseellipse – very – very

similar to a circle…a similar to a circle…a little oval shapedlittle oval shaped

Each planet orbits Each planet orbits the sun in an the sun in an ellipticalelliptical path path

During certain times During certain times of the year…the of the year…the Earth is closer to the Earth is closer to the sun than other times sun than other times of the year.of the year.

Ellipse Animation

RotationRotation

The planets, the The planets, the Sun, moons, and Sun, moons, and the Earth all the Earth all rotate around rotate around their axis, or their axis, or center. center.

All planets, All planets, except Venus and except Venus and Uranus, rotate Uranus, rotate counter-clockwisecounter-clockwise

RevolutionRevolution The orbit of one body around another…The orbit of one body around another…

the the EarthEarth makes one makes one revolutionrevolution of the Sun of the Sun in in 365 days.365 days.

The The MoonMoon makes makes one revolutionone revolution of the of the Earth in Earth in 28 days28 days

All planets orbit the Sun in a counter-All planets orbit the Sun in a counter-clockwise directionclockwise direction

Earth Moon RelationshipEarth Moon Relationship Earth’s only natural Earth’s only natural

satellite.satellite. Size scale – If the Size scale – If the

Earth was a Earth was a basketball with a basketball with a 12” diameter (1 12” diameter (1 foot) then the moon foot) then the moon would be a 3” tennis would be a 3” tennis ball.ball.

Distance scale – Distance scale – using the same scale using the same scale as above – the moon as above – the moon would be 30 feet would be 30 feet away.away.

Correct size scaleCorrect size scaleIncorrect distance scaleIncorrect distance scale

Other Moons of Other Moons of ImportanceImportance

Four of Four of Jupiter’s many Jupiter’s many moonsmoons

Called the Called the Galilean moons Galilean moons (Galileo first (Galileo first found them)found them)

Io has a special Io has a special characteristic…characteristic…

Jupiter’s IoJupiter’s Io Only known Only known

moon to be moon to be volcanically volcanically active in the active in the solar systemsolar system

Saturn’s Many MoonsSaturn’s Many Moons

Titan is heavily studied Titan is heavily studied right now – has right now – has similarities to Earthsimilarities to Earth

Earth’s Moon - Revolution & Earth’s Moon - Revolution & RotationRotation

The moon orbits the The moon orbits the Earth, roughly once Earth, roughly once every 28 days. (once a every 28 days. (once a month)month)

The moon spins on its The moon spins on its axis once every 28 axis once every 28 days. (once a month)days. (once a month)

Therefore, the rotation Therefore, the rotation and the revolution are and the revolution are the same rate.the same rate.

Most moons in the Most moons in the solar system have the solar system have the same tendency – same tendency – phenomenon called phenomenon called tidal locktidal lock

The Dark Side of the The Dark Side of the MoonMoon

There actually is a “dark” side of the moon – at least as seen from Earth

WE ONLY SEE ONE SIDE OF THE MOON BECAUSE IT ROTATES AND REVOLVES AT THE SAME RATE

Lunar Craters & MariaLunar Craters & Maria

The moon’s surface is The moon’s surface is covered with craters covered with craters and maria.and maria.

Impact craters – from Impact craters – from the bombardment of the bombardment of meteors. meteors. Craters more visible than Craters more visible than

craters on Earth craters on Earth - no - no erosion or erosion or vegetative cover on vegetative cover on the moonthe moon

Maria - flat regions Maria - flat regions made by ancient lava made by ancient lava flows. (no volcanic flows. (no volcanic activity on the moon in activity on the moon in millions of years)millions of years)

Crater abundanceCrater abundance

Mare – Greek for seaMare – Greek for sea - Seas of lava- Seas of lava

Apollo Mission Apollo Mission Landing SitesLanding Sites

Phases of the MoonPhases of the Moon

Click below for video clipClick below for video clip

Phases of the MoonPhases of the Moon

Phases of the MoonPhases of the Moon

Moon phases are caused by the Moon phases are caused by the moon’s orbit around the Earth and its moon’s orbit around the Earth and its reflection of the sunreflection of the sun

Waxing indicates the portion of the Waxing indicates the portion of the moon’s surface we see is getting moon’s surface we see is getting largerlarger

Waning indicates the portions of the Waning indicates the portions of the moon’s surface we see is getting moon’s surface we see is getting smallersmaller

Phases of Phases of the Moonthe Moon

Solar EclipsesSolar Eclipses

A solar eclipse occurs A solar eclipse occurs when the Moon passes when the Moon passes between the Sun and between the Sun and the Earth.the Earth.

Occurs during which Occurs during which moon phase?moon phase?

New moonNew moon

During a solar eclipse During a solar eclipse the normally the normally transparent corona transparent corona (outer layer of the (outer layer of the sun) can be seen.sun) can be seen.

Solar EclipsesSolar Eclipses

- Direct shadow – very small area- Direct shadow – very small area

- Secondary shadow – much larger area- Secondary shadow – much larger area

Solar EclipseSolar Eclipse

Lunar EclipsesLunar Eclipses

Occurs when the Occurs when the Moon passes Moon passes into the shadow into the shadow cast by the cast by the EarthEarth

Occurs during Occurs during which moon which moon phase?phase?

FullFull

Lunar EclipseLunar Eclipse

Reason for the Reason for the seasonsseasons

What causes Winter, Spring, What causes Winter, Spring, Summer & Fall?Summer & Fall?

What does this graph tell What does this graph tell you?you?

Distance to the Sun from Earth

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0.97

0.98

0.99

1

1.01

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1-J an 1-Feb 1-Mar 1-Apr 1-May 1-J un 1-J ul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec

Months

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What does this graph tell What does this graph tell you?you?

Distance to the Sun from Earth

0.96

0.97

0.98

0.99

1

1.01

1.02

1-J an 1-Feb 1-Mar 1-Apr 1-May 1-J un 1-J ul 1-Aug 1-Sep 1-Oct 1-Nov 1-Dec

Months

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tanc

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Earth’s path around the sun is not a perfect Earth’s path around the sun is not a perfect circlecircle The path is in the shape of an ellipseThe path is in the shape of an ellipse

Earth is closer to the sun in January (winter in Earth is closer to the sun in January (winter in the northern hemisphere)the northern hemisphere) Distance to the sun has NOTHING to do with Earth’s Distance to the sun has NOTHING to do with Earth’s

seasonsseasons

What causes Earth’s What causes Earth’s Seasons?Seasons?

Click below for video clipClick below for video clip

The Earth’s TiltThe Earth’s Tilt The Earth is tilted on its axis 23.5 degrees. The Earth is tilted on its axis 23.5 degrees. The Earth’s tilt is the reason why we experience different seasons on Earth.The Earth’s tilt is the reason why we experience different seasons on Earth. As the Earth travels around the sun throughout the year, different parts of the As the Earth travels around the sun throughout the year, different parts of the

Earth are tilted toward the direct rays of the sun. Earth are tilted toward the direct rays of the sun.

Equinox and Equinox and SolsticeSolstice

Vernal (spring) or Vernal (spring) or autumnal (fall) autumnal (fall) equiequinox = nox = equequal al day and equal day and equal night.night.

Winter solstice = Winter solstice = shortest day of the shortest day of the year in the NHyear in the NH

Summer solstice = Summer solstice = longest day of the longest day of the year in the NHyear in the NH