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Chapter 23

Chapter 23. Sun, Earth, Moon System. EARTH. Position? Center of the universe? No, the Sun is the center of our solar system ; Earth travels around the Sun. Shape? Flat? Would you fall off if you went too far?

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Chapter 23

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  1. Chapter 23 Sun, Earth, Moon System

  2. EARTH • Position? • Center of the universe? • No, the Sun is the center of oursolar system; Earth travels around the Sun. • Shape? • Flat? Would you fall off if you went too far? • No, the Earth is asphere.Spheres are round, 3-D, and all points on the surface a equidistant (??) from the center. • EVIDENCE: Aristotle: • Earth casts curved shadow • Appearance of approaching ships • Pictures from space probes and satellites.

  3. Motion • Earth rotates around an imaginary line called the axis. • This causes day and night. • One rotation = 24 hours • Rotates 365 times in a year • Earth also revolves around the Sun • Revolution = 1 year

  4. Rotation causes….. • Dayandnight • Rotates counterclockwise or East to West • Changes in position of Sun, stars, planets • Sun rises in the East sets in the West • Observed position changes are due to rotation of Earth.

  5. Revolution One trip around the Sun!!! ** Revolution = length of a year (Closer planets have shorter years, farther planets have longer years) ** Orbit = path the Earth takes around the Sun * Ellipse = shape of the Earth’s orbit.

  6. http://www.mathsisfun.com/earth-orbit.html

  7. Get your partner to say the following!! • SPHERE • REVOLUTION • ROTATION • YEAR • ARISTOTLE • EAST TO WEST • ELLIPSE • ORBIT

  8. Revolution • Closest to Sun in January???? • Farthest in July??? • Then what causes seasons??? TILT

  9. Tilt • The Earth is tilted on its axis at about 23.5o • Daylight hours are longer for the hemisphere tilted toward the SUN!! • This hemisphere also receives more INTENSE RADIATION from the Sun. http://astro.unl.edu/naap/motion1/animations/seasons_ecliptic.html

  10. http://highered.mcgraw-hill.com/sites/007299181x/student_view0/chapter2/seasons_interactive.htmlhttp://highered.mcgraw-hill.com/sites/007299181x/student_view0/chapter2/seasons_interactive.html

  11. Equinoxes • Sun is directly over the equator. • Equal hours of day and night. • Neither hemisphere is pointed toward Sun • Happens twice/year • N. Hemisphere • Spring = March 21 or 22 (Vernal Equinox) • Autumn = September 21 or 22 (Autumnal Equinox)

  12. Solstice • Point at which Sun reaches greatest distance north or south of equator. • Happens twice/year • June 21 or 22 (Summer Solstice) • MOST DAYLIGHT • December 21 or 22 (Winter Solstice) • MOST NIGHT

  13. Get your partner to say the following: • Sphere • Axis • Rotation • Revolution • Ellipse • Equinox • Solstice

  14. Get your partner to say the following: • 24 hours • 365 days • Autumn • Orbit • Tropic of Cancer • June 21 or 22 • March 21 or 22

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