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Motions Within Motions Or, why you always feel like you are just going in circles.

Motions Within Motions Or, why you always feel like you are just going in circles. Stars : Rise in the east, set in the west. On a yearly cycle which stars are visible at night changes.

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Motions Within Motions Or, why you always feel like you are just going in circles.

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  1. Motions Within MotionsOr, why you always feel like you are just going in circles. Stars:Rise in the east, set in the west.On a yearly cycle which stars are visible at night changes. Sun:Rises in the east, sets in the west.On a yearly cyclethe following occur:length of day changes, seasons, “height” of the sun at noon, andwhich stars are visible at night.There are also occasional eclipses. Moon:Rises in the east, sets in the westand this coincides with the tides. Goes through phases on a near monthly basis. Full moon seems to bring out werewolves and odd behavior. There are also occasional eclipses. Planets:Rise in the east, set in the west.Pass through constellations on their own schedule. Occasionally reverse direction for short periods. Change in brightness and exhibit phases. Color Coded Reasons for these observations Earth’s Rotation All the Planets Revolve Around the Sun The Earth’s Axis of Rotation is Tilted

  2. Summary of Lunar Phases • The phase of the Moon is the portion of the Moon facing the Sun that can be seen from Earth. • New Moon: None of the visible Moon is bright. • Crescent Moon: Less than half of the visible Moon is bright. • Quarter Moon: Half of the visible Moon is bright. (The term quarter comes from what part of the cycle it is in.) • Gibbous Moon: More than half of the visible Moon is bright. • Full Moon: The entire visible Moon is bright. • Only half of the Moon is ever visible from Earth. • The Moon is a sphere. • Only half of the moon is ever lit by the sun. • The Moon is still a sphere. • Hence which phase is seen depends on the current Sun-Earth-Moon configuration. • For a new moon the lit half of the Moon is the half of the Moon not facing the Earth. • For a full moon the lit half of the Moon is the half of the Moon facing the Earth. • http://bcs.whfreeman.com/dtu6e/pages/bcs-main.asp?i=02090.04&v=category&ns=0 Animation of Sun-Earth-Moon Configuration causing phases.

  3. Modeling Sun, Earth, and Moon The light bulb is Sun, your head the Earth and a Styrofoam ball is the Moon. Light Bulb = Sun Your Head = Earth Styrofoam Ball = Moon Moon revolves around the Earth in a counterclockwise direction as seen from above the North Pole. Top of your head is the North Pole. Notice that the room is not pitch black. This is mainly because of light reflecting off of the walls. Obviously, this is an excusable, minor flaw in our model. Sunlight Since the Moon is a sphere that only half of it can ever be lit by the Sun at any given moment (though reflected sunlight off the Earth dimly illuminates the Moon as well). Of course the sunlit half of the Moon is always the half closest to the Sun. Being a sphere also results in only half of the Moon ever be seen from Earth at any given moment.

  4. New Moon on Monday Does anyone get this joke? Hold up the Styrofoam ball between your head and the light bulb. Light Bulb = Sun Your Head = Earth Styrofoam Ball = Moon New Moon The angle between the Sun and the Moon as seen from Earth is 0º. Sunlight This configuration of Sun, Earth, and Moon corresponds to the lunar phase of a New Moon. From Earth none of the sunlit half of the Moon can be seen during a New Moon. What angle between the Sun and the Moon is needed for a First Quarter Moon?

  5. First Quarter Moon While facing the light bulb hold up the Styrofoam ball to your left, now turn your head to face the ball. Warning: This is commonly called a half moon since half of the sunlit portion is visible from Earth, but astronomers have named it First Quarter Moon because the Moon is one quarter of the way through its cycle. 90º The angle between the Sun and the Moon as seen from Earth is 90º. Sunlight First Quarter Moon This configuration of Sun, Earth, and Moon corresponds to the lunar phase of the First Quarter Moon. From Earth, half (not a quarter) of the sunlit half of the Moon can be seen during the First Quarter Moon.

  6. Full Moon Fever Hold up the Styrofoam ball with your head between the ball and the light bulb. Notice that you have to hold the ball slightly above your head for it not to be eclipsed by your shadow. Why do we not have lunar eclipses every month? Light Bulb = Sun Your Head = Earth Styrofoam Ball = Moon Full Moon The angle between the Sun and the Moon as seen from Earth is 180º. 180º Sunlight This configuration of Sun, Earth, and Moon corresponds to the lunar phase of a Full Moon. From Earth, all of the sunlit half of the Moon can be seen during a Full Moon. What angle between the Sun and the Moon is needed for a Third Quarter Moon?

  7. Third Quarter Moon While facing the light bulb hold up the Styrofoam ball to your right, now turn your head to face the ball. Light Bulb = Sun Your Head = Earth Styrofoam Ball = Moon Third Quarter Moon 270º The angle between the Sun and the Moon as seen from Earth is 270º. Ok, so it is 90º if you go in the direction counter to the Moon’s revolution. Sunlight This configuration of Sun, Earth, and Moon corresponds to the lunar phase of the Third Quarter Moon. From Earth half (not a quarter) of the sunlit half of the Moon can be seen during the Third Quarter Moon.

  8. Diagram of Configuration vs Phase Third Quarter Moon Waning Crescent Moons Waning Gibbous Moons New Moon Full Moon Earth Sunlight Waxing Crescent Moons Waxing Gibbous Moons First Quarter Moon

  9. Using your head Forget the Styrofoam ball for a few minutes. Determine the time of day for someone sitting on your nose. Western horizon Top of your head is the North Pole. Time: Noon Sun is directly overhead Eastern horizon Sunlight Your peripheral vision to the right is what is seen on the western horizon. Your peripheral vision to the left is what is seen on the eastern horizon. Will you rotate your head to the left or right to simulate the Earth’s rotation?

  10. Rotating your head Rotating your head toward your left to simulate the Earth’s rotation, you find the Sun more to your right. If you just turn 45 degrees, then the sun is 45 degrees to your right, or 45 degrees above the western horizon. Western horizon Time: Afternoon ~3:00pm Sun is in the western sky Eastern horizon Sunlight Your peripheral vision to the right is what is seen on the western horizon. Your peripheral vision to the left is what is seen on the eastern horizon. Will you rotate your head to the left or right to simulate the Earth’s rotation?

  11. Rotating your head Continuing to rotate to the left another 45 degrees, the sun is now at a 90 degree angle (right angle) to your nose. So in your peripheral vision to your right you can just barely see the light. Hence this corresponds to a setting Sun. Western horizon Eastern horizon Sunlight Time: Sunset 6:00pm Sun is on the western horizon

  12. Beating it into your head As you continue to rotate your head think about what time of day/night it is. Eastern horizon Time: Midnight Sun is directly behind your head Western horizon Sunlight As you may have noticed, you cannot actually see the sun during the night. Hence unlike during the day, you cannot simply gauge the hour by a quick glance at the Sun. As it turns out, when we add the moon’s position and phase it frequently becomes possible to calculate the time even at night.

  13. Sunrise on your head Time: Sunrise 6:00am Sun is on the Eastern horizon Eastern horizon Western horizon Sunlight Once the light becomes visible to your left, you have achieved sunrise.

  14. Now do you get it? We are looking down on the North Pole Time: 6:00am Sun is rising on Eastern horizon Time: Noon Sun is directly overhead Time: Midnight Sun is not visible Earth Sunlight Time: 6:00pm Sun is setting on Western horizon Your position on Earth determines your time of day by determining the position of the Sun in your sky.

  15. New Moon at Noon So the New Moon is seen directly overhead at noon. Light Bulb = Sun Your Head = Earth Styrofoam Ball = Moon Western horizon New Moon Eastern horizon Sunlight

  16. New Moon in Afternoon So the New Moon is seen in the western sky at ~3:00pm in the afternoon. Light Bulb = Sun Your Head = Earth Styrofoam Ball = Moon Western horizon New Moon Eastern horizon Time: Afternoon ~3:00pm Sun is in the western sky Sunlight

  17. Sun and New Moon Set Together Western horizon Eastern horizon New Moon Sunlight Time: Sunset 6:00pm Sun is on the western horizon

  18. New Moon at Midnight Both the New Moon and the Sun are not seen during the night. Eastern horizon Time: Midnight Sun is directly behind your head New Moon Western horizon Sunlight

  19. New Moon at Sunrise Both the New Moon and the Sun rise together. Time: Sunrise 6:00am Sun is on the Eastern horizon Eastern horizon Western horizon New Moon Sunlight Now try this for the other lunar phases. See if you can answer the questions about phases at this point, then proceed and check your answers.

  20. Time of Day and Phases of the Moon New Moon Time: Noon Moon is directly overhead Time: 6:00am Moon is rising Time: Midnight Moon is not visible New Moon Earth Sunlight Time: 6:00pm Moon is setting

  21. Time of Day and Phases of the Moon First Quarter Moon Time: 6:00am Moon is not visible Time: Noon Moon is rising Time: Midnight Moon is setting Earth Sunlight Time: 6:00pm Moon is directly overhead First Quarter Moon

  22. Time of Day and Phases of the Moon Full Moon Time: 6:00am Moon is setting Time: Midnight Moon is directly overhead Time: Noon Moon is not visible Full Moon Earth Sunlight Time: 6:00pm Moon is rising

  23. Time of Day and Phases of the Moon Third Quarter Moon Time: 6:00am Moon is directly overhead Third Quarter Moon Time: Noon Moon is setting Time: Midnight Moon is rising Earth Sunlight Time: 6:00pm Moon is not visible

  24. Sheer Lunacy: Other Observations of the Moon The side not facing the Sun can often be seen, though it is dimmer. Rises in the east, sets in the west on a 25 hour 50 minute cycle. Tides on Earth also have a 25 hour 50 minute cycle. Goes through phases on a 29.5 day cycle. The spring and neap tides on Earth have a 29.5 day cycle. The same side of the moon always faces Earth (Synchronous Orbit). Eclipses occur on a very complex schedule with observations of lunar eclipses being more common than solar eclipses.

  25. Earth lighting up Moon Sunlight reflecting off the surface of the Earth lights up the Moon as well. Earth Earth reflects 37% of the incident light Moon reflects 7% of the incident light Sunlight

  26. Relate Time and Position on Earth The Moon is revolving around the Earth during the 23.93 hours it takes Earth to rotate. Hence the Earth has to complete a little bit more than one rotation to get the Moon back in the same position in the night sky. Moon’s position 25h50m later Full Moon Earth Sunlight Additional 28.5° Rotation takes 1 hour 50 minutes 360° Rotation takes 23.93 hours Why is this not 24 hours?

  27. The Moon revolves around the Earth. Sidreal Month It is how long it takes the Moon to pass through a 360º orbit. It is 27.3 days. Synodic Month It is how long it takes the Moon to return to the same phase. It is 29.5 days. http://bcs.whfreeman.com/dtu6e/pages/bcs-main.asp?i=02090.05&v=category&ns=0 Animation of the two types of months. Full Moon Moon has to go more than 360º around the Earth to return to Full Moon phase. This is because the Earth is revolving around the Sun. Full Moon

  28. The phase of the Moon is the portion of the Moon facing the Sun that can be seen from Earth. • New Moon: None of the visible Moon is bright. • Crescent Moon: Less than half of the visible Moon is bright. • Quarter Moon: Half of the visible Moon is bright. (The term quarter comes from what part of the cycle it is in.) • Gibbous Moon: More than half of the visible Moon is bright. • Full Moon: The entire visible Moon is bright. • Only half of the Moon is ever visible from Earth. • The Moon is a sphere. • Only half of the moon is ever lit by the sun. • The Moon is still a sphere. • Hence which phase is seen depends on the current Sun-Earth-Moon configuration. • For a new moon the lit half of the Moon is the half of the Moon not facing the Earth. • For a full moon the lit half of the Moon is the half of the Moon facing the Earth. • http://bcs.whfreeman.com/dtu6e/pages/bcs-main.asp?i=02090.04&v=category&ns=0 Animation of Sun-Earth-Moon Configuration causing phases.

  29. Diagram of Sun-Earth-Moon causing lunar phases from page 12 of your text.

  30. Naming the Moon During lab two semesters ago, I was asked about harvest moons and blue moons. Though I was only partly right about blue moons. I completely botched harvest moons. Blue Moon: Definition One: The second of two full moons in a single month. It is uncommon since the cycle of phases of the moon is 29.5 days (synodic month) which is almost a month. (I got this part) Definition Two: The third of four full moons occurring in a season. Again this is uncommon since the cycle of phases of the moon is 29.5 days and seasons are ~91 days (365/4=91.25). (Found this out from Zoom Astronomy at Enchanted Learning: http://www.enchantedlearning.com/subjects/astronomy/moon/Phases.shtml Another writer challenges both of these definitions as being created after the phrase “Once in a Blue Moon” and suggests some other possibilities. I think this sounds well considered. http://www.rog.nmm.ac.uk/leaflets/blue/blue.html Harvest Moon: The full moon that occurs closest to the autumnal equinox. The time change of the rising of moon from one night to the next is less than at other times of the year (the reason is complex and addressed by Larry Gedney at http://www.gi.alaska.edu/ScienceForum/ASF7/789.html). This results in the near full gibbous moons and the full moon lighting the fields for harvest for a longer period. The Farmer’s Almanac defines several other names for particular full moons. http://www.farmersalmanac.com/astronomy/moonnames.html An interesting depository of moon facts and explanations is Keith’s moon page: http://home.hiwaay.net/~krcool/Astro/moon/ He even addresses why the moon sometimes appears other colors:http://home.hiwaay.net/~krcool/Astro/moon/moonorange/ Keith Cooley appears to be as geeky as I am.

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