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# Moon and earth cycles (teach)

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Helps explains day, night,summer, winter for the elementary student. URL's for some very good visuals are included.

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### Moon and earth cycles (teach)

1. 1. Cycles related to movement of objects in the solar systemBy Moira Whitehouse PhD NASA
2. 2. On Earth we notice some cycles that occurat regular intervals.Some of these cycles are day andnight, years, seasons, moon phasesand tides.These cycles are determined by how theEarth, the Sun and the Moon move relativeto one another in space.
3. 3. Cycles (Effect) Cause(s)Day and night Earth rotating one rotation=one day or 24 hoursYears Earth revolving or orbiting the Sun One revolution or one orbit = one yearSeasons Earth’s axis on a tilt and Earth orbiting the Sun One revolution= 4 seasons summer, fall, winter, springMoon phases Moon orbiting the Earth One revolution=8 moon phasesTides Moon’s gravity pulling on the Earth’s oceans Two high tides and two low tides every day
4. 4. Why do we have day and night?We have day because there is sun light onour side of the planet.We have night because there is no sunlight on our side of the planet.
5. 5. Sunlight Sunlight Day time Night time http://starchild.gsfc.nasa.govThe side of the Earth facing the Sunexperiences day time.The side of the Earth facing away from theSun experiences night time.
6. 6. As the Earth circles the sun it also rotateson it axis (an imaginary line passingthrough the North and South poles).
7. 7. As it rotates only half of the Earth at a time is in the sun light. In that half it is day time. The other half is in shadow, the sun is not visible and it is dark. In that half it is night time. The Earth’s rotation causes every part ofhttp://sos.noaa.gov/ the earth to have both day and night time.
8. 8. Our clocks and calendars are based on oneday being 24 hours long. As can be seen bythis diagram,that’s abouthow it takes forthe Earth tomake onerotation on itsaxis.
9. 9. Sunrisecomingto theHorn ofAfrica
10. 10. Cycles Cause(s)Day and night Earth rotating one rotation=one day or 24 hoursYears Earth revolving or orbiting the Sun One revolution or one orbit = one yearSeasons Earth’s axis on a tilt and Earth orbiting the Sun One revolution= 4 seasons summer, fall, winter, springMoon phases Moon orbiting the Earth One revolution=8 moon phasesTides Moon’s gravity pulling on the Earth’s oceans Two high tides and two low tides every day
11. 11. How is our year based on the relationshipbetween Earth and Sun?Years: Earth revolving or orbiting the Sun One revolution or one orbit = one year
12. 12. While rotating on its axis every day, theEarth is also making a very long triprevolving around (or orbiting) the Sun.The amount of time it takes for the Earthto make one complete revolution aroundthe Sun is one year or 365 ¼ days.Every four years we have leap year inwhich we add one day to the calendarto make up for the four one-fourth days.
13. 13. One trip (oribt) around the Sun (point A back to point A)takes Earth one year of travel time. That is how peoplecame up with the idea to measure time in years. A
14. 14. Cycles Cause(s)Day and night Earth rotating one rotation=one day or 24 hoursYears Earth revolving or orbiting the Sun One revolution or one orbit = one yearSeasons Earth’s axis on a tilt and Earth orbiting the Sun One revolution= 4 seasons summer, fall, winter, springMoon phases Moon orbiting the Earth One revolution=8 moon phasesTides Moon’s gravity pulling on the Earth’s oceans Two high tides and two low tides every day
15. 15. Why is the weather different at different timesof the year? Why do we have seasons? Seasons: Earth’s axis on a tilt and Earth orbiting the Sun One revolution= 4 seasons summer, fall, winter, spring
16. 16. SeasonsParmetheon planet
17. 17. We will look at the two reasons for seasons:1. The Earth orbiting the Sun Without this there would be no seasons, but there would also be nothing else.2. The tilt of the Earth on its axis as it orbitsthe Sun Is the reason we have seasons, as we will see.
18. 18. If the Earth’s axis werestraight up and down asshown in this picture,there would be noseasons. Weather, yes,but no seasonal patterns.But it is not, it is tilted asshown in this picture.And now we shall seehow that causes theseasons.
19. 19. Just how much is the Earth tilted? The axis of the Earth is tilted 23.5 degrees.Wikipedia Commons
20. 20. 23.5º The northern axis of the Earth happens to point within one degree to Polaris, a fairly bright starNorth we call the North Star.Star
21. 21. Because of the tilt of the earth, during certainpositions in its orbit of the Sun the Earth’s NorthernHemisphere is tilted toward the sun; and six monthslater and on the opposite side of the orbit, theSouthern Hemisphere is tilted toward the sun. Southern Hemisphere tilted towards the Sun Northern Hemisphere tilted towards the Sun
22. 22. SpringOr, from another view pointSummer SummerSummer Winter Summer http://www.seed.slb.com/ Permission is granted to make copies of this document for educational purposes only. Fall http://www.seed.slb.com/ Permission is granted to make copies of this document for educational purposes only. http://www.seed.slb.com/ Permission is granted to make copies of this document for educational purposes only.
23. 23. We can see that in the warmer “summer”months, the Earth is not closer to the sunas sometime people might guess.It is actually how direct the sun’s raysstrike the Earth that determines seasonaltemperatures.A given amount of heat energy must cover agreater amount of space (and is thereforeweaker) the further it is from the equatorwhen it strikes the earth.
24. 24. As seen here, the sun’s incoming energy (we will call it fourunits) is more concentrated and covers a smaller circle nearerthe equator than the same four units covering a much largercircle closer to the poles.Lower latitudes near the earth’s equator, therefore, receive agreater concentration of incoming energy and are warmerthan higher latitudes.
25. 25. This animated visual shows the Earth moving in orbit through the seasons.http://esminfo.prenhall.com/science/geoanimations/animations/01_EarthSun_E2.html
26. 26. Fall in the Spring in the Northern Southern Hemisphere HemisphereWinter in theNorthern Summer in theHemisphere Northern Hemisphere Winter in theSummer in Southernthe Southern HemisphereHemisphere Spring in the Fall in the Northern Southern Hemisphere Hemisphere http://www.srh.noaa.govhttp://www.srh.noaa.gov
27. 27. Cycles Cause(s)Day and night Earth rotating one rotation=one day or 24 hoursYears Earth revolving or orbiting the Sun One revolution or one orbit = one yearSeasons Earth’s axis on a tilt and Earth orbiting the Sun One revolution= 4 seasons summer, fall, winter, springMoon phases Moon orbiting the Earth One revolution=8 moon phasesTides Moon’s gravity pulling on the Earth’s oceans Two high tides and two low tides every day
28. 28. Phases of the Moon
29. 29. What causes the Moons phases?The Moon goes through these phasesbecause: 1) the Moon is revolving around theEarth, and 2) the Moon is reflecting sunlighttowards the Earth.Half of the Moon is always lit, not just theportion we see: however, sometimes weonly see the lit portion of the Moon basedon where it is in its orbit.
30. 30. Before an in-depth study of the Moon’s phases, we will look at the Moon’s relationship with the Earth.The moonrotates onits axis as itorbits theEarth. NASA
31. 31. At the same time as the Earth is rotatingand orbiting (revolving around) the Sun,the Moon is rotating and orbiting the Earth. Earth’s axis Moon orbits the Earth Earth orbits the Sun
32. 32. Now to that “in-depth” look at the phasesof the Moon.There are eight phases that the moongoes through and they always occur inthe same order.The Suns light seems to move from rightto left across the surface of the Moon.
33. 33. The phases of the Moon are:1) New Moon,2) Waxing Crescent3) First Quarter,4) Waxing Gibbous5) Full Moon,6) Waning Gibbous7) Last Quarter8) Waning CrescentAnd back to the New Moon.
34. 34. New Waxing First Moon Crescent QuarterWaxing Full WaningGibbous Moon Gibbous Third Waning New Quarter Crescent Moon
35. 35. Let’s look at the phases of the moon on a calendar. Choose the present month and year. Notice that the change from phase to phase is very gradual and takes about a month for the cycle.http://www.tutiempo.net/en/moon/phases_3_2011.htm
36. 36. Select Moon Phases in the following URLfor an outstanding animation of the Moonand its phases. http://www.valdosta.edu/~cbarnbau/astro_de mos/frameset_moon.html
37. 37. As shown in the diagram, the new moonoccurs when the moon is positionedbetween the earth and sun. The entireilluminated(lit up) side ofthe moon is onthe back partof themoon–the half thatwe cannot see. http://www.wiseg orilla.com
38. 38. At a full moon, the earth, moon, and sun arein approximately lined up, just as the newmoon, but this time the moon is on theopposite side of theearth. As a result,the entire sunlitpart of the moonis facing us. Theshadowed portionis entirely hiddenfrom view. http://www.wise gorilla.com
39. 39. The first quarter and third quarter moons(both often called a "half moon"), occur whenthe moon is at a 90 degree angle with respectto the Earthand Sun. So we areseeing exactly halfof the Moonilluminated andhalf in shadow. http://www.wise gorilla.com
40. 40. It takes for the Moon 29.5 days toorbit the Earth, about one month.(Also the amount of time from onenew moon to the next).
41. 41. Cycles Cause(s)Day and night Earth rotating one rotation=one day or 24 hoursYears Earth revolving or orbiting the Sun One revolution or one orbit = one yearSeasons Earth’s axis on a tilt and Earth orbiting the Sun One revolution= 4 seasons summer, fall, winter, springMoon phases Moon orbiting the Earth One revolution=8 moon phasesTides Moon’s gravity pulling on the Earth’s oceans Two high tides and two low tides every day
42. 42. What causes tides in the ocean? The Moon’s gravity pulling on the Earth causes the tides.
43. 43. To understand Moon tides we must havesome idea about gravity. Gravity is a force. Gravity is a force that pulls.Every object has gravity.So every object pulls on every otherobject.The more mass an object has, the harderit pulls.
44. 44. We will use two hypothetical planets for ourexample. Both the blue and green planetsare pulling on each other. Which one pulls harder?
45. 45. This should help us see that the more mass an object has the stronger its gravity. Moon Earth The Earth obviously has more mass thanBut the Moon’s gravity is also pulling on the Moon and it pulls harder.the Earth. So hard that the oceans swell So much harder that theever it passes. in antoward the Moon where Moon is held Wecall this high tide. Earth as though by some orbit around the magically strong string.
46. 46. Hopewell rocks at at low and high tides.
47. 47. Ocean tides are caused by the gravity of the moon pulling on the ocean’s water. As a result of this pull of gravity, theocean’s water bulges toward the Moon onevery rotation of the Earth. This bulge iscalled high tide and it occurs about every 12hours—twice a day. Low tide occursbetween high tides.
48. 48. The point is, because of the Moon’s gravity,the ocean’s water bulges toward the Moon onevery rotation of the Earth.
49. 49. Would the tides be greater if the Sun andMoon were lined up? Why? Sun
50. 50. Open this website and choose tides. All good, but these two especially important for understanding tides. http://www.valdosta.edu/~cbarnbau/astro_demos/frameset_moon.html`
51. 51. Cycles Cause(s)Day and night Earth rotating one rotation=one day or 24 hoursYears Earth revolving or orbiting the SunSeasons In Review... One revolution or one orbit = one year Earth’s axis on a tilt and Earth orbiting the Sun One revolution= 4 seasons summer, fall, winter, springMoon phases Moon orbiting the Earth One revolution=8 moon phasesTides Moon’s gravity pulling on the Earth’s oceans Two high tides and two low tides every day