Transcript Day & Night
Page #136 Feb. 5, 2013 Focus: Day & Night, Seasons, Rotation & Revolution Objective: explain how the movement of the Earth affect different cycles EQ: In what ways do planets move? What is affected by this movement? HW: lesson review questions Warm Up: 1. What is gravitational pull and how does it affect our solar system? 2. How do we get day and night? OH Last Class! Why do the planets revolve around the sun? What would happen without gravity? What is gravitational pull and how does it affect our solar system? http://www.youtube.com/ watch?v=RIBNgx2hlyU Day & Night Thinking Ahead • What is a day? • What is a year? • Are days and years the same on other planets? Why do you think so? http://player.discoveryeducation.co m/index.cfm?guidAssetId=D62132 6A-36AB-47BF-9CC777BE8EB7589A • DIRECTIONS: • 1. Color and label the sun • 2. Color the day time half of the Earth green and blue • 3. Color the night time half of the Earth black The Earth spins on its axis • The spinning is called ROTATION • The direction of rotation is counterclockwise if you are looking at it as if you were floating over the North Pole http://vortex.plymouth.edu/sun/sun.html Each morning, the sun rises in the east and sets in the west. Read more: http://www.universetoday.com/18117/why-does-the-sun-rise-in-theeast-and-set-in-the-west/#ixzz2JxtfwWlH As the Earth spins, part of the Earth is facing toward the Sun, and part is facing away from the Sun. The part of the Earth facing the Sun has daytime Day and Night • The Earth rotates around once in 24 hours • The time it takes the Earth to rotate completely around once is what we call a day. • It's Earth's rotation that gives us night and day • http://www.onr.navy.mil/focus/spacescienc es/observingsky/motion1.htm So the reason we have day and night is because the Earth rotates. Rotate means to turn. The Earth rotating on its ______ axis gives us day and night. Earth’s axis is the imaginary line that goes through the center of the Earth. Rotation Rotation: Planets spin on an axis One Rotation = Day Fast Rotation = short day Slow Rotation = long day Rotation is measured in hours. Earth’s Rotation: 24 hours (1 day) But guess what! Rotating isn’t the only way the Earth moves in space! The Earth also revolves. Revolve – When one object moves around another object How long does one revolution take? It takes the Earth one year, or 365 ¼ days to orbit the sun. Does anyone know what orbit means? Orbit The path that an object follows as it revolves around another object. Revolution Revolution: Planets revolve around the sun Revolution = Year Fast Revolution = short year You would be older Closer to the sun Slow Revolution = long year You would be younger Farther from the sun Revolution is measured in _days___ Earth’s Revolution 365 days (1 year) Planet Callisto Rotation Period 36 hours (hours) Revolution Period (days) Ganymede Europa Dione 567 hours 3,085 hours 6,396 days 350 days 909 hours 2,349 days 54,938 days Other planets Which planet do you think rotates the fastest? Why? Which planet do you think has the longest revolution? Why? Rotation Data Planet Length of Day Mercury 58.6 Earth days Venus 243.02 Earth days Earth 24 hr Mars 24 hr 37 min Jupiter 9 hr 55 min Saturn 10 hr 32 min Uranus 17 hr 14 min Neptune 16 hr 6 min Rotational Speeds Planet Length of Day Rotational Speed (km/h) Mercury 58.6 Earth days 10.9 Venus 243.02 Earth days 6.5 Earth 24 hr 1670 Mars 24 hr 37 min 867 Jupiter 9 hr 55 min 45600 Saturn 10 hr 32 min 37000 Uranus 17 hr 14 min 10900 Neptune 16 hr 6 min 8460 Revolutions Why are the revolutions of each planet different than Earth’s revolution? Mercury • Smallest planet • Closest to Sun, moves around fastest (88 days) • no tilt of axis so poles are cold Venus • Nearly the same size as Earth • Slowest rotation of any planet (243 days) • Spins backwards Can see it in the night sky without a telescope! Earth Liquid water – lots! - at surface 23 degree axis tilt (seasons!) Earth’s Rotation: 24 hours (1 day) Earth’s Revolution: 365 days (1 year) Can see it without a telescope! Mars Can see it in the night sky without a telescope! 25 degree axis tilt (seasons!) Rotates once every ~24 hours and orbits the Sun once every 687 days Very cold No liquid water at surface; ice in poles Jupiter diameter – 11x Earth largest planet completes one orbit in 4,333 Earth days, or almost 12 Earth years. Jupiter rotates faster than any other planet. It takes 9 hours 56 minutes to spin around once on its axis, compared with 24 hours for Earth. Which means it has the shortest day. Saturn • 9x the size of Earth • 11 hour rotation / 29 year orbit Seasons What do think causes the seasons? http://nix.ksc.nasa.gov/info What Causes Earth’s Seasons? • Earth’s axis is tilted 23.5 degrees – it always points in the same direction (Polaris, the North Star) as we orbit our Sun once a year • This tilt causes the hemispheres to alternate in the amount of our Sun’s light and heat they receive through the year http://www.lpi.usra.edu/education/skytellers/seasons/about.shtml Northern Hemisphere Summer More daylight hours, more direct sunlight http://www.lpi.usra.edu/education/skytellers/seasons/about.shtml But why do we have four seasons? It’s because the Earth’s axis is tilted. Take a good look at our globe. It‘s not tilted like that because it looks nice. No way. That’s the way the Earth is tilted in space. That tilt gives us seasons! Look at this diagram. Notice how the Earth is always tilted in the same direction. As the revolves the part of Earth tilted Earth __________ toward the sun changes. During part of the year, the North Pole points away from the sun. winter_____ This season is _. During part of the year the North Pole tilts towards the sun. This season is summer ________. When the North Pole is tilted toward the Sun, the Sun travels higher overhead in the sky. The Sun’s rays shine straighter down on that part of the Earth. It is summer in that part of the Earth. It’s like pointing a flashlight at a piece of paper. When you hold the flashlight straight above the paper, the rays from the flashlight shine down straighter. When the North Pole is tilted away from the Sun, the Sun stays lower in the sky. It is then winter in that part of the Earth. If you point your flashlight at a piece of paper at an angle, the rays from the flashlight spread out. In the Spring and Fall EQUINOX A day lasts 12 hours and a night lasts 12 hours at all latitudes. http://k12.ocs.ou.edu/teachers/reference/e quinox.gif Sunlight strikes the earth most directly at the equator. In the Summer and Winter SOLSTICE During the winter the Northern Hemisphere day lasts fewer than 12 hours and the Southern Hemisphere day lasts more than 12 hours. http://k12.ocs.ou.edu/teachers/ref erence/solstice.gif During the winter solstice, the North Pole has a 24-hour night and the South Pole has a 24hour day. Sunlight strikes the earth most directly at the Tropic of Capricorn. In the Summer and Winter SOLSTICE During the summer solstice the Northern Hemisphere day lasts more than 12 hours and the Southern Hemisphere day lasts fewer than 12 hours. During the summer, the North Pole has a 24-hour day and the South Pole has a 24-hour night. http://k12.ocs.ou.edu/teachers/refe rence/solstice.gif Sunlight strikes the earth most directly at the Tropic of Cancer. Why does the earth experience seasons? Because the Earth is tilted, different parts of the planet get different amounts of sunlight at different times of the year. Independent Practice 1. Draw pictures A and B. 2. Label the picture that shows the red dot is in the season of summer. Label the picture that shows the red dot in the season of winter. A. B. http://ithacasciencezone.com/earthzone/lessons/07meteor/daylight.jpg Page # January 17, 2011 Title: Rotation and Revolution Objective: analyze how Earth’s movement affects day and night HW: all work is due by Wednesday, check calendars Warm-Up: Does the Earth move around the Sun? How do we get day and night? RIGHT PAGE 52 December 2, 2008 Title: Lets Start a Revolution ! Objective: Describe a planet and the effects of a planet’s movement. Words to Know:orbit - path of an object in space as it moves around another object. year- amount of time a planet takes to revolve around the sun. day- how many hours does it take a planet to rotate on its axes.