1. Earth’s Moon

2. Origin and Properties of the Moon The Moon’s Motions Earth’s Moon

3. The Moon The moon revolves around the earth with a period of about 29 ½ days ~ one month! Facts about the Moon… We see the moon changes its appearances and position in the sky with approximately 30- day cycle. Unlike the stars, Moon can also be seen during the day. We also see that the Moon is always involved in eclipses, and Its position seems to be well correlated with the tide of the ocean. Understanding the motion of the Moon with respect to the Sun and the Earth will explain these phenomena.

4. Scientists think the moon formed after a large object, about the size of a planet, hit Earth. VOCABULARY Origin and Properties of the Moon Earth’s Moon 1. Earth is hit off- center by a planet- sized object. 2. The impact heats and deforms both bodies. Some rocky debris remains in orbit around Earth. 3. The debris ring, made of rock from the outer layer of both objects, gradually coalesces, forming the moon. crater micrometeoroid maria mascons rille ray regolith

5. Much of the material broken away from the earth goes into orbit. The moon reassembles in this orbit - it takes about a month of violent collisions. Earth is speeded up in rotation as a result of the collision. This theory is consistent with: 1.) composition of lunar rocks, which is similar to the composition of the crust of the earth; 2.) evidence that the moon had a molten surface for 200 million years; and 3.) the lack of magnetic field for the moon, which together with its low density implies it has very little iron in its core. Impact theory

6. Earth’s Moon The same side of the moon always faces Earth. Dark areas called maria are great basins and level plains on the moon. They are younger than the lighter lunar highlands. Lunar highland rocks are older than mare rocks. Mare Highland Maria: Extensive dark areas on the moon that represent great basins and level plains.

7.  Most lunar craters were caused by the impact of meteoroids; rays of shattered rock and dust were splashed out by the impacts.  Regolith is the loose rock material covering the moon’s surface. It is formed as micrometeoroids smash into and erode the moon’s surface. Earth’s Moon Crater: A bowl- shaped depression on the surface of a moon or a planet, usually caused by the impact of a meteorite. Micrometeoroid: Tiny rock fragment no larger than sand grains that travels through space. Lunar rocks have textures similar to Earth rocks but differ in composition.

11. Rille : A trenchlike valley running through the bedrock of lunar maria, believed to have formed after the cave-in of the roof of a tunnel that had transported lava. Earth’s Moon Ray: A bright streak of shattered rock and dust that radiates from a lunar crater.

12. The moon’s orbit is tilted 5 degrees relative to the plane of Earth’s orbit. The moon’s movement around Earth causes it to rise later each day and to go through phases. VOCABULARY The Moon’s Motions Earth’s Moon Light from the Sun Waning Crescent Waxing Crescent New Moon Full Moon Waning Gibbous Waxing Gibbous Last Quarter First Quarter Phases of the Moon phases waxing waning gibbous umbra penumbra lunar eclipse solar eclipse

13. Lunar Phases This causes the “phases” of the Moon Waxing Moon – increasing from day to day Waning Moon – decreasing from day to day Sunlight illuminates half of the Moon –it’s a ball and the Sun is shining on it from one direction

14. Lunar Phases (cont) New Moon –The Moon is on the same part of the sky as the Sun and rises and sets with the Sun Full Moon –The Moon is in the opposite side of the sky as the Sun and rises when the Sun sets and sets when the Sun rises New Moon Waxing Crescent Moon Waxing Half Moon Waxing Gibbous Moon Full Moon Waning Gibbous Moon Waning Half Moon Waning Crescent Moon New Moon …

15. The Phase of the Moon The phase of the Moon depends on the relative position between the Sun, the Earth, and the Moon…

16. Moonrise/Moonset The time the Moon rises and sets is correlated to its phase Phase of the MoonRiseZenithSet New Moon6 am6 pm Waxing Half Moon6 pm Full Moon6 pm6 am Waning Half Moon6 amNoon New Moon6 amNoon Midnight 6 pm

17. Why do we Always See the Same Side of the Moon? The rotation period of the Moon with respect to the universe is exactly the same as the rotation period of the Moon around the Earth. Is this a coincidence? No!  It’s due to Tidal Locking

18. Tidal Locking A tidally locked body takes just as long to rotate around its own axis as it does to revolve around its partner. This synchronous rotation causes one hemisphere constantly to face the partner body. The Moons orbital period is 27.3 days. It also rotates once on its axis in 27.3 days (synchronous rotation) resulting in Tidal Locking.

19. “Dark Side” of the Moon The Moon doesn’t have a “dark side” –Everywhere on the Moon, the Sun rises and sets once per month It has a side which faces away from us –During a New Moon, the far side is completely illuminated

20. A lunar eclipse occurs when Earth passes between the sun and the moon, and the moon is within Earth’s shadow. A solar eclipse occurs when the moon passes between the sun and Earth, and the moon’s shadow falls on Earth. The Moon’s Motions Total Solar Eclipse SunEarth Moon Sun Earth Penumbra Moon Umbra lunar eclipse solar eclipse

21. Eclipses Eclipses occur when the Sun, the Earth and the Moon all lie along a straight line –They must line up in all 3 dimensions + time –the Moon’s orbit is tilted 5 o with respect to the ecliptic, so there are only two times a year when the paths overlap

22. Solar and Lunar Eclipses Eclipse: The total or partial obscuring of one celestial body by another… The obscuration can be either One celestial body blocking the view to the other: –Solar eclipse---Moon blocking Earth’s view to the Sun… One celestial body is in the shadow of another: –Lunar eclipse---Moon is in the shadow of the Earth… Lunar eclipse image from http://www.mreclipse.com

23. Lunar Eclipse Umbra: The darkest part of the shadow cast by the moon or by Earth. Penumbra: The area of partial shadow surrounding the darkest part of the shadow of the Earth or moon. Lunar eclipses can only occur during a full moon. The maximum time a lunar eclipse can last is 3 hours and 40 minutes.

24. Solar Eclipse Solar eclipses can only occur during a new moon. The maximum time for a total solar eclipse is 7 minutes and 40 seconds. Solar eclipses are visible in a narrow path a maximum of 167 miles wide (269km.)

25. Total Solar Eclipse of 21 June 2001 from Zimbabwe See Richard Monk’s webpage on eclipses: www.williams.edu/ astronomy/IAU_eclipses/ Bailey’s Beads Solar Corona “Diamond Ring”

26. Solar Eclipse Forecast Solar eclipses from 2004 to 2030 Knowing the orbit of the Earth and the Moon, we can now calculate the time and path of solar eclipses with great accuracy.

27. Eclipses: Summary The parties involved: Sun, Moon, and Earth Motion of the Moon around Earth: 1.29 ½ day revolution of the Moon around the Sun 2.Tilt (~5º) of the lunar orbit (around the Earth) w.r.t. the Ecliptic plane (Earth’s orbital plane around the Sun) 3.The precession of the lunar orbit w.r.t. Earth-Sun direction Solar eclipse happens when the Moon is between the Earth and the Sun. The size and distance of the Moon need to be just right for us to see total eclipse. –The changing distance between the Earth and the Moon explains the occurrences of the total and ring solar eclipses. –The changing distance between the Earth and the Sun, and the Earth and the Moon explains the difference in the duration of the solar eclipses. Lunar eclipse happens when Earth is between the Moon and the Sun.

28. Eclipse facts 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. Eclipses very often occur in threes, alternating lunar, solar and lunar.

29. 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. The maximum time for an annular solar eclipse is 12 minutes 24 seconds. Lunar eclipses can occur up to 3 times a year.

30. Eclipse facts Solar eclipses can occur at least 2 and no more than 5 times a year. Lunar eclipses are visible over an entire hemisphere. 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.

31. Eclipse facts The cycle of eclipses repeats every 18.6 years called the saros. The eclipse shadow moves at 2,000 mph at the Earth's poles and 1,000 mph at the Earth's equator.

32. Uniform water level Moon Moon’s orbit The twice-daily rise and fall of Earth’s oceans— known as the tide—is a result of gravitational pulls from the moon and the sun. VOCABULARY Tides The Moving Ocean Low tide Direct high tide Indirect high tide tides perigee apogee

33. Tides reach different levels depending on Earth’s location in relation to the moon and sun. High tides are higher and low tides are lower when the moon, sun, and Earth are aligned. High tides are not as high and low tides are not as low as usual when the moon and sun are not in line with Earth. VOCABULARY Tides The Moving Ocean The twice-daily rise and fall of Earth’s oceans— known as the tide—is a result of gravitational pulls from the moon and the sun. tides perigee apogee

34. Earth Moon Moon Spring Tides The gravitational affects of the moon and sun combine to influence the flow of the oceans on Earth. New Moon Phase of the moon? Full Moon Phase of the moon? Moon New Moon Phase of the moon? Higher high tides and lower low tides

35. Earth Moon Moon First Quarter Phase of the moon? Third Quarter Phase of the moon? Neap Tides The gravitational affects of the moon and sun fight each other with their influence on the flow of the oceans on Earth. Moon Third Quarter Phase of the moon? Lowest high tides and highest low tides

36. Tides Perigee: The point closest to Earth in the moon’s orbit. Apogee: The point farthest to Earth in the moon’s orbit.

40. Tides & Consequences This little tidal behavior goes both ways! The Earth rises tides on the Moon. The Earth "brakes" the Moon's rotation AND the braking is complete! Synchronous Rotation of the Moon and its orbital period! (27.3 days!) Moon also brakes the Earth's Rotation Moon's orbit is growing because of all of this interaction. We see a permanent "near" and "far side" of the Moon. The length of the "day" is increasing!  From fossil reef corals of about 4  10 8 years old - daily growth/annual growth  400 days/year ~ 22 hours a day!  Day is increasing about 0.001 seconds/century. Therefore, the day is getting longer, Moon looks smaller, and tides are weakening.

41. The Lunar Program and Flagstaff

51. Two members of the prime crew of the Apollo 17 lunar landing mission participate in lunar surface extravehicular activity simulation training at the Kennedy Space Center, Florida.

52. “Genesis Rock" returned by the Apollo 15 lunar mission

53. During the Apollo 12 mission in 1969, commander Pete Conrad retrieves equipment from the Surveyor 3 probe, which landed on the moon three years earlier. This picture, taken by astronaut Alan Bean, shows Apollo 12's lunar module in the far distance.

57. Apollo 17 astronaut Harrison Schmitt standing next to boulder at Taurus-Littrow during third extravehicular activity (EVA-3).

58. This photo was taken by Apollo 17 commander Eugene Cernan. It is of lunar module pilot Harrison Schmitt standing in front of a large split boulder on the Moon. Apollo 17 was the last of the Apollo Moon landing missions.

60. A. Origin of the Moon 1. Development of the Moon B. Properties and Features of the Moon 2. The Moon Today 1. Lunar Maria 2. Lunar Highlands 3. Lunar Craters and Rays 4. Lunar Soil VOCABULARY I. Origin and Properties of the Moon Earth’s Moon astronomy meteoroid crater micrometeoroid maria mascons rille ray regolith

61. A. The Moon’s Orbit B. The Moon’s Phases D. Solar Eclipses C. Lunar Eclipses VOCABULARY II. The Moon’s Motions Earth’s Moon phases waxing waning gibbous umbra penumbra lunar eclipse solar eclipse

62. A. The Moon and Tides B. The Sun’s Effect on Tides C. Tidal Range VOCABULARY III. Tides The Moving Ocean tides perigee apogee