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Unit 3: Earth’s Moon and Sun

Unit 3: Earth’s Moon and Sun. I. The Origin of the Moon The most acceptable theory is: The Great Impact Theory Moon formed 4.5 b.y.a . Earth and planet sized body collided.

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Unit 3: Earth’s Moon and Sun

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  1. Unit 3: Earth’s Moon and Sun • I. The Origin of the Moon • The most acceptable theory is: The Great Impact Theory • Moon formed 4.5 b.y.a. • Earth and planet sized body collided. • Debris from impact settled into orbit around Earth and was pulled together by Earth’s gravity = accretion. (1/2 billion years)

  2. Meteoroids impacted the moon creating a molten “magma ocean”. • Lighter, less dense, materials floated to surface. • Moon cooled and hardened. • Additional impacts created craters, mountains, and basins. • 4-3 b.y.a. impacts slowed as Earth & Moon absorbed debris.

  3. Iron rich magma rose to surface and filled in impact basins = lunar maria. • For 3 billion years the interior has been quiet but exterior continues to be bombarded by micrometeoroids. Meteoroids = > sand grain to 1000’s of kg Micrometeoroids = </= sand grain

  4. CW: Lunar Timeline • Create a timeline starting with 5 billion years ago when our sun and Earth were created and ending with the present. • Include all of the details of what occurred to create and form the moon we know today.

  5. II. Phases of the Moon

  6. How and why it all happens… • The Moon, Earth, and Sun are all involved. • As the Moon orbits the Earth, its position with respect to the Sun changes which determines its phases. • It takes 27.3 “Earth days” for the Moon to revolve around the Earth, but a “Moon day” is 29.5 days. Why?

  7. Answer • The moon’s appearance depends on the position of the moon with respect to the sun as seen from the Earth. • The moon revolves around the earth in 27.3 days, but takes 29.5 days to go from new moon to new moon because of the sun’s rays shining at a different angle. • Because the Earth has traveled around the sun, it takes roughly 2.2 days for the moon to get back to a position where the angle of the sun’s rays will create the necessary effect, ie. the moon to not be visible.

  8. http://upload.wikimedia.org/wikipedia/commons/4/46/Moon_phases_en.jpghttp://upload.wikimedia.org/wikipedia/commons/4/46/Moon_phases_en.jpg

  9. The Relationship Between the Moon, Earth, and Sun.  Sun 

  10. Moon Phase Terminology

  11. Full Moon • 9-24-07

  12. Full Moon • 9-25-07

  13. Waning Gibbous • 9-29-07

  14. Waning Gibbous • 9-30-07

  15. Waning Gibbous • 10-2-07

  16. Last Quarter • 10-3-07

  17. Waning Crescent • 10-4-07

  18. Waning Crescent • 10-5-07

  19. Waning Crescent • 10-7-07

  20. New Moon • 10-9-07 • The moon is between the Earth and the Sun.

  21. Waxing Crescent • 10-14-07

  22. Waxing Crescent • 10-15-07

  23. Waxing Crescent • 10-17-07

  24. First Quarter • 10-19-07

  25. Waxing Gibbous • 10-21-07

  26. Waxing Gibbous • 10-23-07

  27. Full Moon • 10-24-07 • The Earthis between the Moon and the Sun.

  28. Eclipses Solar  Lunar 

  29. Why don’t we have lunar eclipses once a month? • If the Moon's orbit around the Earth were in the same plane as the Earth's around the Sun (the ecliptic,) we would indeed have a monthly eclipse. However, the Moon's orbit is inclined about 5 degrees to the Earth's orbit. The Moon passes through the ecliptic only twice a month at a pair of points called the nodes. The rest of the time the Moon is either above or below the plane of the Earth's orbit and does not pass directly through the Earth's shadow.

  30. Steps of a Lunar Eclipse • When the Moon is in the penumbra, the outer part of the Earth's shadow, it is difficult to notice any change, but you may notice a color change. • During an eclipse, a small amount of light still reaches the Moon, reflected from sunrises and sunsets going on around the edges of our planet. This can make the Moon appear from nearly invisible, to murky brown to a beautiful blood red colour. The more dust there is in the Earth's atmosphere, the darker the Moon will be during totality. • But as the Moon begins to move into the darker portion of the Earth's shadow, you will be able to watch the Moon disappear in shadow from its left edge.“Volcanic” Eclipse 

  31. Solar and Lunar Eclipse Facts • The maximum time a lunar eclipse can last is 3 hours and 40 minutes. • The longest time the Moon can stay in totality is 1 hour 40 minutes. • The maximum time for a total solar eclipse is 7 minutes and 40 seconds. Lunar eclipses can only occur during a full moon. • Solar eclipses can only occur during a new moon. • A Solar eclipse always occurs two weeks before or after a lunar eclipse. • Solar eclipses are visible in a narrow path a maximum of 167 miles wide (269km.) • At any geographic position on the Earth, a total solar eclipse occur an average of once every 360 years.

  32. Believe it or not! Life could survive on the Moon! The Apollo 12 astronauts, Conrad, Gordon and Bean, brought back life from the Moon: a terrestrial bacterium found on a piece of foam inside the camera of the Surveyor 3 lander. The bacterium survived for 2 and a half years on the lunar surface!

  33. III. Lunar Features & Properties A. Rotation on axis = 27.3 days Revolution around Earth = 27.3 days Therefore, we see the same side ALWAYS!! B. Physical Properties 1. Diameter: 3476 Km; > ¼ Earth’s 2. Mass: 1/80 Earth’s 3. Density: 3.3 g/cm3 (Earth’s: 5.5g/cm3) ***Lower density supports Impact Theory!! Why? Less dense material knocked off Earth at impact.

  34. Surface Features 1. Near side: 65 km crust Far side: 150 km crust WHY??? D. Lunar Craters and Rays Meteoroid strikes cause… …moon’s “soil” to move outwards, called “ejecta”, from the impact, resulting in a crater. … “ejecta” to fly outwards in a linear pattern, resulting in a ray.

  35. E. “Lunar Soil” – Not true soil…. Why? 1. It’s called regolith. a. Ground up rock materials from meteoroid impacts. b. Small amounts of glassy material is found, caused by high temperatures, but slow cooling.

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