Earth, Moon, and Sun Earth, Moon, and Sun SystemSystem

Earth’s Magnetic FieldEarth’s Magnetic FieldEarth has a Earth has a

magneticmagnetic field field that protects us that protects us

from harmful from harmful radiationradiation from from

the sun.the sun.

Earth’s Magnetic FieldEarth’s Magnetic FieldEarth’s magnetic field is:Earth’s magnetic field is:•ConcentratedConcentrated at two ends at two ends of an imaginary of an imaginary magnetic magnetic axis running from Earth’s axis running from Earth’s north magnetic pole to its north magnetic pole to its south.south.

•Tilted about Tilted about 11.511.5 degrees degrees from the from the geographicgeographic axis axis

Earth’s Magnetic FieldEarth’s Magnetic FieldEarth’s magnetic Earth’s magnetic field:field:

•Changes Changes slowlyslowly over time.over time.

•Called the Called the magnetospheremagnetosphere

•Responsible for Responsible for auroras.auroras.

Earth’s Magnetic FieldEarth’s Magnetic FieldWhat are auroras?What are auroras?

•The The magnetosphere magnetosphere deflects harmful deflects harmful radiationradiation from the from the Sun, a Sun, a stream stream of of particles called particles called solarsolar wind.wind.

Earth’s Magnetic FieldEarth’s Magnetic FieldWhat are auroras?What are auroras?•These particles from These particles from the Sun produce the Sun produce charged charged particlesparticles in in Earth’s atmosphere Earth’s atmosphere that spiral along that spiral along Earth’s magnetic Earth’s magnetic fieldfield lines towards the lines towards the magnetic poles and magnetic poles and collidecollide with with atomsatoms in in the atmosphere. the atmosphere. These collisions cause These collisions cause atomsatoms to to emitemit light. light.

Earth Orbits the SunEarth Orbits the SunEarth’s orbit is slightly Earth’s orbit is slightly

ellipticalelliptical..

An ellipse is like a An ellipse is like a slightly flattened slightly flattened circlecircle

or or eggegg-shaped.-shaped.

Earth As a PlanetEarth As a PlanetEarth is the only planet Earth is the only planet with characteristics that with characteristics that make it possible for make it possible for lifelife

as we know it to as we know it to survive.survive.

Earth as a PlanetEarth as a PlanetEarth resembles Earth resembles VenusVenus more than more than any other planet any other planet in:in:

•SizeSize

•Both have Both have atmospheresatmospheres with with carbon carbon dioxidedioxide

Time and SeasonsTime and SeasonsHumans have used Humans have used movements ofmovements of Earth Earth, , the the MoonMoon, and the , and the SunSun to measure to measure timetime for thousands of for thousands of years.years.•Earth makes a Earth makes a complete rotational complete rotational turn once in about turn once in about 2424 hours.hours.•Earth’s actual Earth’s actual rotation is rotation is 2323 hours, hours, 5656 minutes, and minutes, and 4 4 seconds.seconds.

Time and SeasonsTime and SeasonsRevolution Measures Revolution Measures YearsYears

•The time that it takes to The time that it takes to make a complete make a complete rotationrotation or or orbitorbit around around the the sun sun is is 365365 days days which is our Earth year.which is our Earth year.

Time and SeasonsTime and SeasonsWhy do seasons change?Why do seasons change?•They change primarily due They change primarily due to the to the tilttilt of the Earth on its of the Earth on its axis axis in relationship to the in relationship to the sun (changes in the angle sun (changes in the angle of sunlight hitting certain of sunlight hitting certain parts of Earth).parts of Earth).•In short, Earth’s seasons In short, Earth’s seasons are influenced by Earth’s are influenced by Earth’s rotation, revolutionrotation, revolution, and , and tilttilt of its axis.of its axis.

Time and SeasonsTime and SeasonsWhy do we have more Why do we have more daylight in summer daylight in summer than winter?than winter?•The hemisphere of the The hemisphere of the Earth that is tilted Earth that is tilted toward the Sun toward the Sun receives more hours of receives more hours of daylight…another daylight…another reason it is reason it is warmerwarmer in in the summer.the summer.

Time and SeasonsTime and SeasonsEquinoxes and Equinoxes and SolsticesSolstices

Two times a year, Two times a year, the sun is the sun is directlydirectly over the Earth’s over the Earth’s equator. This is equator. This is called an called an equinoxequinox..

Time and SeasonsTime and SeasonsDuring an During an equinoxequinox, the , the number of number of daylight daylight hours equals the hours equals the number of number of nighttime nighttime hours all over the hours all over the world.world.•These occur around These occur around March 20March 20thth or 21 or 21stst, and , and September 22September 22ndnd or 23 or 23rdrd..

Time and SeasonsTime and SeasonsThe solstice is the point at The solstice is the point at which the Sun reaches its which the Sun reaches its greatest greatest distancedistance, north or , north or south of the equator, and it south of the equator, and it appears to “appears to “standstand”, or stop ”, or stop moving. This occurs on June moving. This occurs on June 2121stst or 22 or 22ndnd, and December 21, and December 21stst or 22or 22ndnd..•During summer solstice, there During summer solstice, there are more hours of are more hours of daylightdaylight than than during any other day of the during any other day of the year, and during winter solstice, year, and during winter solstice, it is the it is the shortestshortest daylight day of daylight day of the year.the year.

http://www.materialworlds.com/sims/SolarSystem/FourSeasons1View/install.html

Movement of the MoonMovement of the MoonIt takes It takes 27.327.3 days days for the Moon to for the Moon to revolve once revolve once around earth and around earth and two more days for two more days for the Moon to line up the Moon to line up with with EarthEarth and the and the SunSun again, thus a again, thus a complete complete lunar lunar phase takes phase takes 29.529.5 days (a synodic days (a synodic month)month)

Movement of the MoonMovement of the MoonThe same The same sideside of of the the moon moon always always appears toward appears toward Earth because it Earth because it takes takes 27.327.3 days to days to rotate rotate onceonce on its on its axis, the same axis, the same amount of time it amount of time it takes to revolve takes to revolve onceonce around Earth. around Earth.

How does the moon affect How does the moon affect Earth?Earth?

TIDESTIDES

Tides are caused by a Tides are caused by a giant giant wavewave produced produced by the by the gravitational gravitational pulls of the pulls of the SunSun and and the the MoonMoon..

The actual wave is only The actual wave is only 1-21-2 m, but has a m, but has a wavelength of wavelength of thousandsthousands of of kilometerskilometers. .

How does the moon affect How does the moon affect Earth?Earth?

TIDESTIDES

Even though it is Even though it is smaller smaller than the sun, the moon has than the sun, the moon has a greater a greater effecteffect on tides on tides than the sun because it is than the sun because it is closercloser. .

How does the moon affect How does the moon affect Earth?Earth?

TIDESTIDES

When the moon and When the moon and sun line up, high tides sun line up, high tides are much are much higherhigher and and low tides are much low tides are much lowerlower. This is called a . This is called a springspring tide. tide.

How does the moon affect How does the moon affect Earth?Earth?

TIDESTIDES

When the moon and When the moon and sun are at sun are at rightright angles angles to each other, the high to each other, the high tide is not as tide is not as high high and and the the lowlow tide is not as tide is not as low, producing a low, producing a neapneap tide.tide.

Phases of the MoonPhases of the Moon

The moon The moon ““shinesshines” because ” because it is reflecting it is reflecting sunlight sunlight from its from its surfacesurface..

Moon phases are Moon phases are the changing the changing appearancesappearances of of the Moon as seen the Moon as seen from Earth.from Earth.

Phases of the MoonPhases of the MoonNew MoonNew Moon•Moon is between the Moon is between the EarthEarth and the and the SunSun..•Cannot be Cannot be seen seen (except during a special (except during a special alignment)alignment)

Phases of the MoonPhases of the MoonWaxing PhasesWaxing Phases•LightedLighted portion that we portion that we see appears to be see appears to be largerlarger each night. each night.•Said to be in the Said to be in the waxing waxing gibbous gibbous phase phase until it reaches the full until it reaches the full moon phase.moon phase.

Phases of the MoonPhases of the MoonWaning PhasesWaning Phases•The lighted portion that The lighted portion that we see appears to be we see appears to be smallersmaller each night. each night.

EclipsesEclipsesSolar EclipseSolar Eclipse•Occurs when the Occurs when the moonmoon moves directly between moves directly between the the SunSun and and EarthEarth and and casts a shadow on part of casts a shadow on part of Earth.Earth.•The The darkestdarkest portion of portion of the Moon’s shadow is the Moon’s shadow is called the called the umbraumbra..

EclipsesEclipsesSolar EclipseSolar Eclipse•The The lighterlighter shadow cast on shadow cast on Earth’s surface Earth’s surface is called the is called the penumbrapenumbra..

EclipsesEclipsesLunar EclipseLunar Eclipse•Occurs when Occurs when Earth’s Earth’s shadowshadow falls on the moon.falls on the moon.

Moon’s SurfaceMoon’s SurfaceCraters, Maria, Craters, Maria, and Mountainsand Mountains•Many Many depressions depressions (craters) were (craters) were formed by formed by meteoritesmeteorites, , asteroidsasteroids, and , and cometscomets striking the striking the surface of the surface of the moon.moon.

Moon’s SurfaceMoon’s SurfaceMariaMaria•Dark-colored relatively Dark-colored relatively flatflat regions on the regions on the Moon’s surface.Moon’s surface.

RegolithRegolith•DebrisDebris on the Moon’s on the Moon’s surface.surface.

Moon’s InteriorMoon’s InteriorThe moon’s interior is The moon’s interior is believed to have a believed to have a crustcrust, upper , upper mantlemantle, , lower lower mantlemantle, and a , and a corecore..

Moon’s OriginMoon’s Origin

Capture TheoryCapture TheoryThe moon was The moon was capturedcaptured by Earth’s by Earth’s gravitygravity..

Binary Accretion TheoryBinary Accretion TheoryThe moon The moon condensedcondensed from the same material that from the same material that formed the formed the EarthEarth..

Moon’s OriginMoon’s Origin

Fission TheoryFission TheoryA glob of A glob of molten molten material was ejected material was ejected from Earth while it was from Earth while it was still in its still in its moltenmolten stage. stage.

Moon’s OriginMoon’s OriginGiant Impact TheoryGiant Impact Theory•A A MarsMars sized object sized object collided with Earth.collided with Earth.•The cores of the 2 bodies The cores of the 2 bodies combinedcombined and and settled settled toward the center of the toward the center of the larger larger object.object.•GasGas and and debris debris condensed into a large condensed into a large mass forming the mass forming the moonmoon..