Student Astronomical Society First Meeting!!!!! Wednesday, September 14 7:00 PM 5 th  Floor of the Physics Building There ...
Astronomy 1010 Introduction to Astronomy Lecture 10
Why does the moons appearance change?
Why do we see different phases of the Moon? <ul><li>The motion of the Moon in its orbit around the Earth causes us to see ...
The Phases of the Moon From Earth, we see different portions of the Moon’s surface lit by the sun, causing the phases of t...
U.S. Naval Observatory Astronomical Applications Department Sun or Moon Rise/Set Table for One Year Sky Gazer Program – Ex...
The Phases of the Moon Evening Sky
The Phases of the Moon Morning Sky
Suppose that on a given evening you notice that the Moon has a crescent shape. This simple observation tells you <ul><li>t...
The dark side of the moon <ul><li>Is there a dark side of the moon? </li></ul>
Is there a dark side to the moon? Earth exerts tidal forces on the moon’s rocky interior ->  It is rotating with the same ...
The Moon is seen to keep one face toward Earth at all times. If viewed from a point directly above the plane of the planet...
Synodic vs Sidereal  <ul><li>Sidereal period = time for moon to complete one full orbit of the earth </li></ul><ul><li>Syn...
Sidereal Period  <ul><li>The Moon orbits Earth in a  sidereal period  of  27.32 days. </li></ul>27.32 days Earth Moon Fixe...
Synodic Period <ul><li>The Moon’s  synodic period  (to reach the same position relative to the sun) is 29.53 days (~ 1 mon...
The size of the moon
Lunar motions Inclination of the Moons orbit 5 o Ecliptic plane Moon ’ s  Orbital Plane
Libration http://upload.wikimedia.org/wikipedia/commons/c/c0/Lunar_libration_with_phase2.gif
 
Earthrise from lunar orbit, Apollo 8 Earth rising, from Japan’s Kaguya spacecraft
Eclipses
Eclipses <ul><li>Eclipses are shadows </li></ul><ul><li>If the earth is directly between the moon and the sun    lunar ec...
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Ast1010 lecture 10 post

  1. 1. Student Astronomical Society First Meeting!!!!! Wednesday, September 14 7:00 PM 5 th Floor of the Physics Building There will be refreshments!!! Student Astronomical Society First Meeting!!!!! Wednesday, September 14 Wednesday, September 14 Wednesday, September 14 7:00 PM 5 th Floor of the Physics Building There will be refreshments!!! 7:00 PM 5 th Floor of the Physics Building There will be refreshments!!! 7:00 PM 5 th Floor of the Physics Building There will be refreshments!!!
  2. 2. Astronomy 1010 Introduction to Astronomy Lecture 10
  3. 3. Why does the moons appearance change?
  4. 4. Why do we see different phases of the Moon? <ul><li>The motion of the Moon in its orbit around the Earth causes us to see different amounts of the Earth's shadow falling on the Moon. </li></ul><ul><li>The motion of the Moon in its orbit around the Earth causes us to see different amounts of the sunlit side of the Moon. </li></ul><ul><li>The distance of the Moon from the Earth changes because of the elliptical orbit of the Moon, causing the sunlit side of the Moon to move relative to the Earth. </li></ul><ul><li>The rotation of the Moon around its own axis causes us to see different amounts of the sunlit side of the Moon. </li></ul>
  5. 5. The Phases of the Moon From Earth, we see different portions of the Moon’s surface lit by the sun, causing the phases of the moon.
  6. 6. U.S. Naval Observatory Astronomical Applications Department Sun or Moon Rise/Set Table for One Year Sky Gazer Program – Explore, Phases of the Planets, Phases of the Moon Moon Phases http://www.valdosta.edu/~cbarnbau / astro_demos/frameset_moon.html
  7. 7. The Phases of the Moon Evening Sky
  8. 8. The Phases of the Moon Morning Sky
  9. 9. Suppose that on a given evening you notice that the Moon has a crescent shape. This simple observation tells you <ul><li>that at that particular time the Moon is closer to the Sun than you are. </li></ul><ul><li>that at that particular time the Moon is farther from the Sun than you are. </li></ul><ul><li>that the line from you to the Moon is exactly at right angles to the line from you to the Sun. </li></ul><ul><li>nothing at all about where the Moon is in space compared to you and the Sun. </li></ul>
  10. 10. The dark side of the moon <ul><li>Is there a dark side of the moon? </li></ul>
  11. 11. Is there a dark side to the moon? Earth exerts tidal forces on the moon’s rocky interior -> It is rotating with the same period around its axis as it is orbiting Earth (tidally locked) -> We always see the same side of the moon facing Earth
  12. 12. The Moon is seen to keep one face toward Earth at all times. If viewed from a point directly above the plane of the planetary system, how does it have to rotate to maintain this alignment? Q? <ul><li>It must rotate once per year as Earth and Moon orbit the Sun together. </li></ul><ul><li>It must rotate once per day. </li></ul><ul><li>It must not rotate at all, since we always see the same face from Earth. </li></ul><ul><li>It must rotate once per month, or once per orbit around Earth. </li></ul>
  13. 13. Synodic vs Sidereal <ul><li>Sidereal period = time for moon to complete one full orbit of the earth </li></ul><ul><li>Synodic period = time between successive New Moons. </li></ul>
  14. 14. Sidereal Period <ul><li>The Moon orbits Earth in a sidereal period of 27.32 days. </li></ul>27.32 days Earth Moon Fixed direction in space
  15. 15. Synodic Period <ul><li>The Moon’s synodic period (to reach the same position relative to the sun) is 29.53 days (~ 1 month). </li></ul>Fixed direction in space Earth Moon Earth orbits around Sun => Direction toward Sun changes! 29.53 days
  16. 16. The size of the moon
  17. 17. Lunar motions Inclination of the Moons orbit 5 o Ecliptic plane Moon ’ s Orbital Plane
  18. 18. Libration http://upload.wikimedia.org/wikipedia/commons/c/c0/Lunar_libration_with_phase2.gif
  19. 20. Earthrise from lunar orbit, Apollo 8 Earth rising, from Japan’s Kaguya spacecraft
  20. 21. Eclipses
  21. 22. Eclipses <ul><li>Eclipses are shadows </li></ul><ul><li>If the earth is directly between the moon and the sun  lunar eclipse  the moon is in the Earth ’s shadow </li></ul><ul><li>If the moon is directly between the earth and the sun  solar eclipse  the earth is in the moon ’s shadow </li></ul><ul><li>Why don ’t we have an eclipse every month? </li></ul>
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