1. Sun-Earth-Moon System Chapter 28.3

2. Daily Motions The sun rises in the east & sets in the west. The sun rises in the east & sets in the west. This is a result of Earths rotation on its axis This is a result of Earths rotation on its axis The time period from one sunrise or sunset to the next is called solar day The time period from one sunrise or sunset to the next is called solar day Our timekeeping system Our timekeeping system

3. Annual Changes Annual changes (seasons) are the result of Earth’s orbital motion around the sun – revolution & its axial tilt Annual changes (seasons) are the result of Earth’s orbital motion around the sun – revolution & its axial tilt The plane in which Earth The plane in which Earth orbits about the sun is called the ecliptic

4. Earth’s Tilt Earth’s axis is tilted relative to the ecliptic at approximately 23.5˚ Earth’s axis is tilted relative to the ecliptic at approximately 23.5˚ As Earth orbits the Sun one hemisphere (N or S) is always facing the sun As Earth orbits the Sun one hemisphere (N or S) is always facing the sun

5. Solstices Summer Solstice Summer Solstice The sun’s maximum altitude in the sky in the N. Hemisphere. The sun’s maximum altitude in the sky in the N. Hemisphere. The sun is directly overhead at the Tropic of Cancer which is at 23.5˚ N latitude The sun is directly overhead at the Tropic of Cancer which is at 23.5˚ N latitude Occurs around June 21 st Occurs around June 21 st each year # of daylight hours for # of daylight hours for the N. Hemisphere is at its maximum

6. Solstices Winter Solstice Winter Solstice The sun has reached its lowest altitude in the sky The sun has reached its lowest altitude in the sky The sun is directly overhead the Tropic of Capricorn at 23.5˚ S. latitude The sun is directly overhead the Tropic of Capricorn at 23.5˚ S. latitude Occurs around Occurs around December 21 st each year # of daylight hours in # of daylight hours in the N. Hemisphere is the N. Hemisphere is at its minimum

7. Equinoxes Autumnal Equinox (Fall) Autumnal Equinox (Fall) Vernal Equinox (Spring) Vernal Equinox (Spring) Earth’s axis is not pointed at the sun Earth’s axis is not pointed at the sun Both hemispheres receive equal amounts of sunlight Both hemispheres receive equal amounts of sunlight - Equal lengths of day & night The sun is directly The sun is directly overhead at the equator

8. Altitude of Sun Earth is closest to the sun in January and farthest from the sun in July. Earth is closest to the sun in January and farthest from the sun in July. The position of the Sun affects how directly sunlight strikes Earth. The position of the Sun affects how directly sunlight strikes Earth. When the sun is at a lower altitude, the sun strikes the Earth is spread out over a larger area. When the sun is at a lower altitude, the sun strikes the Earth is spread out over a larger area.

9. Altitude of Sun Motions of the Sun Simulator

10. Phases of the Moon The apparent shape of the moon depends upon the changing relative positions of Earth. The apparent shape of the moon depends upon the changing relative positions of Earth. As the moon completes one revolution around Earth each month, the growing and shrinking lighted area makes the moon appear to change in shape. As the moon completes one revolution around Earth each month, the growing and shrinking lighted area makes the moon appear to change in shape. Lunar Phase Simulator Lunar Phase Simulator Lunar Phase Simulator Lunar Phase Simulator

11. Phases of the Moon

12. One complete orbit of the moon around Earth takes 27.3 days. One complete orbit of the moon around Earth takes 27.3 days. A complete cycle of the moon’s phases takes 29 ½ days. A complete cycle of the moon’s phases takes 29 ½ days. This 2 ½ day difference is the additional distance the Moon travels to return to original phase This 2 ½ day difference is the additional distance the Moon travels to return to original phase Sidereal vs. Synodic Month Simulation Sidereal vs. Synodic Month Simulation Sidereal vs. Synodic Month Simulation Sidereal vs. Synodic Month Simulation

14. Synchronous Rotation Why do we always see the same side of the moon? Why do we always see the same side of the moon? The Moon’s rotation is equal to its orbital period – revolution The Moon’s rotation is equal to its orbital period – revolution so it spins once each time it goes around the earth so it spins once each time it goes around the earth Animation: Animation: Synchronous Rotation Synchronous Rotation Synchronous Rotation Synchronous Rotation

15. Lunar Eclipse A lunar eclipse occurs when a A lunar eclipse occurs when a Full Moon passes into Earth’s shadow. During a lunar eclipse, the moon is faintly visible (reddish color). During a lunar eclipse, the moon is faintly visible (reddish color). You can still see the moon because sunlight is bent by Earth’s atmosphere, which causes a weak illumination of the moon. You can still see the moon because sunlight is bent by Earth’s atmosphere, which causes a weak illumination of the moon.

16. Lunar Eclipse

17. A solar eclipse occurs when the New Moon passes directly between the Sun and Earth and blocks our view of the Sun. A solar eclipse occurs when the New Moon passes directly between the Sun and Earth and blocks our view of the Sun. Total solar eclipse – moon perfectly blocks the Sun’s disk. Total solar eclipse – moon perfectly blocks the Sun’s disk. Partial solar eclipse – moon blocks only portion of Sun’s disk. Partial solar eclipse – moon blocks only portion of Sun’s disk. Annular solar eclipse – Annular solar eclipse – moon is at apogee thus cannot cover the Sun completely. Solar Eclipse

18. Solar Eclipses Partial Solar Eclipse Total Solar Eclipse Annular Solar Eclipse

19. Solar Eclipse

20. Perigee / Apogee The Moon’s distance from Earth increases and decreases as the Moon moves in its elliptical orbit around Earth. The Moon’s distance from Earth increases and decreases as the Moon moves in its elliptical orbit around Earth. The closest point in the Moons orbit to Earth is called perigee The closest point in the Moons orbit to Earth is called perigee The farthest point in the Moons orbit to Earth is called apogee The farthest point in the Moons orbit to Earth is called apogee

21. Perigee / Apogee

22. Earth-Moon Orbit

23. The Tides Every point along the ocean experiences two low tides and two high tides per day. Every point along the ocean experiences two low tides and two 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.

24. Bay of Fundy Highest tidal range in the WORLD!!!

25. The Tides The water of the oceans is pulled toward the moon, which causes high tide. The water of the oceans is pulled toward the moon, which causes high tide. Another high tide occurs on the opposite side of Earth b/c i Another high tide occurs on the opposite side of Earth b/c inertia exceeds the gravitational force. The highest high tides and the lowest low tides occur about twice a month near the full and new moon phases. The highest high tides and the lowest low tides occur about twice a month near the full and new moon phases.

26. The Tides Spring Tides: Spring 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.

27. The Tides Neap Tides: Neap 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

28. Spring Tide / Neap Tide

29. The Tides