2 Daily MotionsEarth’s rotation causes us to see daily rising and setting of the Sun, Moon, and starsRises in the East, sets in the WestWe observe changes in their location due to the Earth rotating
3 Day Length Solar day – time from one noon to the next noon Length of a day is approximately 4 minutes longer than it takes the Earth to make one rotation on its axisFoucault pendulum
4 Earth orbits the sun in a slightly elliptical orbit Annual MotionsEarth orbits the sun in a slightly elliptical orbitPlane of Earth’s orbit is called ecliptic planeThis movement causes us to see different constellations in the sky during different times of year
5 Earth’s tilt The Earth’s axis is tilted 23.5° Axis remains fixed in spaceCycle of seasons is due to this tiltWhen Northern hemisphere points towards the sun = SummerWhen Southern hemisphere points towards the sun = Summer
6 SolsticesThe Sun is overheard at its farthest distance either north or south of the equator
7 Summer Solstice around June 21st In Northern Hemisphere, number of daylight hours reaches its maximumSun is in the sky continuously with the region of the Arctic Circle
8 Winter Solstice Around December 21st In Northern Hemisphere, number of daylight hours is at its minimumSun does not appear in the region within the Arctic Circle
9 EquinoxEqual nightsEarth’s axis is perpendicular to the Sun’s rays and at noon the Sun is directly overhead at the equatorVernal – March 20, 2011Autumn – Sept. 23, 2011
13 Phases of the Moon New Moon = moon is between Earth & Sun So we do not see light reflected off of its surfaceWaxing = lighted area is increasing due to position between Earth & SunCrescent = “sliver” of moon is visible1st Quarter = ½ lit upGibbous = almost Full
17 EarthshineOnly during early crescent phases, “dark” part shines dimly, due to reflect light off the Earth
18 In-Class AssignmentStart “Movements of Earth” WKT
19 27.3 Part BOBJECTIVESDescribe the orbit of the Moon and its effects including cycles and eclipses.Illustrate how the Moon goes through phases..
20 Synchronous RotationMoon rotates with a period equal to its orbit periodSpins only once each time it goes around the Earth
21 Lunar MotionsLunar Month = complete cycle of phases from one New Moon to the nextRotation = 29.5 daysRevolution of Moon = 27.3 daysOrbits around EarthMoon rises and sets 50 minutes later each day
22 Tides Moon’s gravity pulls on Earth and creates bulges of ocean water As Earth rotates, bulges remain aligned with moon
23 Solar Eclipses Moon passes directly between Sun and Earth For more information see pg. 793Moon passes directly between Sun and EarthBlocks sunlightTotal eclipse only visible in small portion of EarthPartial eclipse is seen in larger portion
27 This solar eclipse shows flares (storms) on the edges of the sun!
28 Annular eclipses Eclipse with ring of the Sun visible Moon in apogee Due to the elliptical orbit of Moon causes it to be closer to Earth during parts of its orbitPerigee – closest point of Moon’s orbit to EarthApogee – farthest pointMoon appears smaller
34 Time ZonesBecause of sun’s apparent motion, sun appears highest over different locations at different timesWorld divided into 24 standard time zonesIn each zone, noon is when sun is highest over the center of that zone
35 Earth rotates 15 degrees every hour Time ZonesEarth rotates 15 degrees every hourEach time zone is one hour earlier than the zone to its eastInternational Date Line – point where earth changes from one day to the next
37 Daylight Savings Time Change your clocks November 7th at 2 AM Fall back an hourSpring forward an hourBy changing your clocks, you gain an extra hour of daylight
38 Are calendars tied in with the moon? Day: time it takes Earth to make a full rotationMonth: Time it takes the moon to go from through one cycle
39 Are calendars tied in with the moon? Year: Time needed for the earth to make one orbit (revolution) around the sun ( days – makes us add a day every four years – leap year)The days of the week were named after the Sun, moon, and the five known planets.
40 In-class AssignmentFinish “Movements of Earth” WKT