sun-earth-moon system chapter 28.3. daily motions the sun rises in the east & sets in the west....

Sun-Earth-Moon SystemSun-Earth-Moon SystemChapter 28.3Chapter 28.3

Daily MotionsDaily Motions

The sun The sun rises rises in the in the easteast & sets & sets in the in the westwest. . This is a result of Earths This is a result of Earths rotationrotation on its axis on its axis

The time period from one sunrise or The time period from one sunrise or sunset to the next is called sunset to the next is called solar daysolar dayOur timekeeping systemOur timekeeping system

Annual ChangesAnnual Changes

Annual changes (seasons) are the result Annual changes (seasons) are the result of Earth’s orbital motion around the sun – of Earth’s orbital motion around the sun – revolution revolution && its axial tilt its axial tilt

The plane in which EarthThe plane in which Earth

orbits about the sun is orbits about the sun is

called the called the ecliptic ecliptic

Earth’s TiltEarth’s Tilt Earth’s axis is tilted relative to the ecliptic at Earth’s axis is tilted relative to the ecliptic at

approximately 23.5˚approximately 23.5˚ As Earth orbits the Sun one hemisphere (N or S) As Earth orbits the Sun one hemisphere (N or S)

is always facing the sunis always facing the sun

SolsticesSolsticesSummer Solstice Summer Solstice

The sun’s maximum altitude in the sky in the N. The sun’s maximum altitude in the sky in the N. Hemisphere. Hemisphere.

The sun is directly overhead at the Tropic of The sun is directly overhead at the Tropic of Cancer which is at 23.5˚ N latitudeCancer which is at 23.5˚ N latitude

Occurs around June 21Occurs around June 21stst

each yeareach year# of daylight hours for # of daylight hours for

the N. Hemisphere is at the N. Hemisphere is at

its its maximum maximum

SolsticesSolsticesWinter Solstice Winter Solstice

The sun has reached its lowest altitude in the The sun has reached its lowest altitude in the skysky

The sun is directly overhead the Tropic of The sun is directly overhead the Tropic of Capricorn at 23.5˚ S. latitudeCapricorn at 23.5˚ S. latitude

Occurs around Occurs around

December 21December 21stst each each

yearyear# of daylight hours in# of daylight hours in

the N. Hemisphere is the N. Hemisphere is

at its at its minimum minimum

EquinoxesEquinoxes

Autumnal Equinox Autumnal Equinox (Fall) (Fall) Vernal Equinox Vernal Equinox (Spring)(Spring)Earth’s axis is Earth’s axis is notnot pointed at the sun pointed at the sunBoth hemispheres receive equal amounts of Both hemispheres receive equal amounts of

sunlightsunlight- Equal lengths of day &Equal lengths of day &

nightnightThe sun is directly The sun is directly

overhead at the equatoroverhead at the equator

Altitude of SunAltitude of Sun

Earth is Earth is closestclosest to the sun in January and to the sun in January and farthestfarthest from the sun in July. from the sun in July.

The position of the Sun affects how directly The position of the Sun affects how directly sunlight strikes Earth.sunlight strikes Earth.When the sun is at a lower altitude, the sun When the sun is at a lower altitude, the sun

strikes the Earth is spread out over a larger strikes the Earth is spread out over a larger area. area.

Altitude of SunAltitude of Sun

Motions of the Sun Simulator

Phases of the MoonPhases of the Moon

The apparent shape of the moon depends The apparent shape of the moon depends upon the changing relative positions of upon the changing relative positions of Earth.Earth.

As the moon completes one revolution As the moon completes one revolution around Earth each month, the growing and around Earth each month, the growing and shrinking lighted area makes the moon shrinking lighted area makes the moon appearappear to change in shape. to change in shape.

Lunar Phase SimulatorLunar Phase Simulator

Phases of the Moon Phases of the Moon

Phases of the MoonPhases of the Moon

One complete orbit of the moon around One complete orbit of the moon around Earth takes 27.3 days.Earth takes 27.3 days.

A complete cycle of the moon’s phases A complete cycle of the moon’s phases takes 29 ½ days.takes 29 ½ days.This 2 ½ day difference is the additional This 2 ½ day difference is the additional

distance the Moon travels to return to original distance the Moon travels to return to original phasephase

Sidereal vs. Synodic Month SimulationSidereal vs. Synodic Month Simulation

Synchronous RotationSynchronous Rotation

Why do we always see the Why do we always see the same side same side of of the moon?the moon?The Moon’s The Moon’s rotationrotation is is equalequal to its orbital to its orbital

period – period – revolutionrevolutionso it spins once each time it goes around the earthso it spins once each time it goes around the earth

Animation: Animation: Synchronous RotationSynchronous Rotation

Lunar EclipseLunar Eclipse

A A lunar eclipselunar eclipse occurs when a occurs when a

Full Moon Full Moon passes into Earth’s passes into Earth’s

shadow.shadow.During a lunar eclipse, the moon is faintly During a lunar eclipse, the moon is faintly

visible (reddish color) .visible (reddish color) .You can still see the moon because sunlight You can still see the moon because sunlight

is bent by Earth’s atmosphere, which is bent by Earth’s atmosphere, which causes a weak illumination of the moon.causes a weak illumination of the moon.

Lunar EclipseLunar Eclipse

A A solar eclipsesolar eclipse occurs when the occurs when the New Moon New Moon passes directly between the Sun and Earth and passes directly between the Sun and Earth and blocks our view of the Sun.blocks our view of the Sun.

Total solar eclipse Total solar eclipse – moon perfectly blocks the – moon perfectly blocks the Sun’s disk.Sun’s disk.

Partial solar eclipsePartial solar eclipse – moon blocks only portion of – moon blocks only portion of Sun’s disk. Sun’s disk.

Annular solar eclipse Annular solar eclipse – – moon is at apogee thus cannot cover the Sun completely.

Solar EclipseSolar Eclipse

Solar EclipsesSolar Eclipses

Partial Solar Eclipse

Total Solar Eclipse

Annular Solar Eclipse

Solar EclipseSolar Eclipse

Perigee / ApogeePerigee / Apogee

The Moon’s distance from Earth increases The Moon’s distance from Earth increases and decreases as the Moon moves in its and decreases as the Moon moves in its elliptical orbit around Earth. elliptical orbit around Earth.

The The closestclosest point in the Moons orbit to Earth point in the Moons orbit to Earth is called is called perigeeperigee

The The farthestfarthest point in the Moons orbit to point in the Moons orbit to Earth is called Earth is called apogee apogee

Perigee / ApogeePerigee / Apogee

Earth-Moon OrbitEarth-Moon Orbit

The TidesThe Tides Every point along the ocean experiences Every point along the ocean experiences twotwo

low tides and low tides and twotwo high tides per day. high tides per day. ““Semidiurnal Tides”Semidiurnal Tides”

refers to the alternating rise and fall of sea level within a day.

the gravitational attraction of the sun and moon that cause waters of the ocean to swell and recede at different parts of the earth.

Bay of FundyBay of Fundy

Highest tidal range in the WORLD!!!

The TidesThe Tides

The water of the oceans is pulled toward the The water of the oceans is pulled toward the moon, which causes high tide.moon, which causes high tide.

Another high tide occurs on the opposite side Another high tide occurs on the opposite side of Earth b/c of Earth b/c iinertia exceeds the gravitational force.

The highest high tides and the lowest low The highest high tides and the lowest low tides occur about twice a month near the tides occur about twice a month near the fullfull and and newnew moon phases. moon phases.

The Tides The Tides Spring TidesSpring Tides: : occur when the Earth, Sun,

Moon are in a line. The gravitational forces of the Moon and the Sun

both contribute to the tides. Spring tides occur during the full moon and the

new moon. 

The Tides The Tides

Neap TidesNeap Tides:: occur when the gravitational forces of the Moon and the Sun are perpendicular to one another (with respect to the Earth). occur during quarter moons.especially weak tides 

Spring Tide / Neap TideSpring Tide / Neap Tide

The Tides The Tides