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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
