Our Earth in Motion Understanding Time, Tides and Seasons

Transcription

1 Our Earth in Motion Understanding Time, Tides and Seasons minutes Program Synopsis Why does the sun rise in the east? Why does the moon change shape? How do tides happen? This program explains in detail how the Earth and the Moon move with respect to each other and the Sun, why we have day and night and different time zones. Why we have four seasons every year, two tides and the different phases of the moon. This program will enhance student understanding of key concepts that are effectively demonstrated through clear graphics and animation. For more information please visit or contact customer service at or on or fax

2 Our Earth in Motion: Teacher Notes: Jeannette Jolley B.Sc. (La Trobe University) B.Ed. (La Trobe University) Introduction The program starts by showing how the position of the Sun and the Earth s rotation on its axis once every 24 hours gives us day and night, sunrise in the east, sunset in the west, and the 24 different time zones around the world. Because the Earth's axis is tilted at 23 o and the Earth revolves around the sun once every 365¼ days, the two hemispheres are facing towards the sun at different times of the year, giving us the seasons. The Moon revolves around the Earth once every 29 days, and because we can only see the part of the moon that is lit by the sun, we see the phases of new moon, first quarter, full moon and last quarter over these 29 days. The tides are due to the gravitational pull of the Moon and the Sun on the earth s oceans. The oceans are pulled towards these large bodies, particularly towards the Moon because it is closer. Because the Earth spins on its axis once every day, we experience daily changes to the depth of the oceans when that part of the Earth is pointed towards the Moon. Program Rationale The program is aimed at lower secondary students (may be suitable for upper primary too) to help them understand how the Earth and Moon move with respect to each other and to the Sun, why we have day and night and so the different time zones, why we have four seasons every year, two tides and the different phases of the moon. Background Information The Sun is the centre of our solar system, with the nine planets revolving around it in various elliptical orbits. The Earth is the third planet out from the sun. Most planets have smaller bodies, natural satellites called moons that revolve around them. The Earth has one natural satellite called the moon, which has no light of its own. We only see the moon because it reflects light from the sun back to us. It takes 29 days for the moon to complete one revolution around the Earth. The Earth spins on its axis once in 24 hours, and this axis is tilted at 23½ o from the vertical. It takes the Earth 365¼ days to complete one revolution around the sun. This is the length of one year.

3 Our Earth in Motion: DVD Timeline 00:00:00 Introduction 00:00:54 Day and Night 00:07:14 Seasons 00:11:47 Phases of the Moon 00:15:38 Tides 00:20:57 Credits 00:21:30 End program Program Worksheet Before the Program 1. Initiate a class discussion on the cycles of day & night, the tides, the monthly cycle of the moon s phases and the yearly changes in the seasons. 2. Find an aboriginal dreamtime story relating to these concepts and read it to the class to stimulate discussion or kick off some research. 3. Ask the students to research some dreamtime stories and write a summary about how the story tries to explain the storyteller s experiences. 4. Ask the students to record the phases of the moon several times per week over a month. They could also record some times of sunset and/ or sunrise and compare it to the times given in the daily newspapers. They could note the places on the horizon where the sun rises or sets and compare this over a period of time.

4 During the Program Our Earth in Motion: 1. Exactly how long does it take for the Earth to spin once on its axis? 2. The axis is an imaginary line that passes through which two points on the Earth? 3. How long exactly does it take the Earth to revolve around the Sun once? 4. What do we call the time when the Earth rotates and the first rays of sunlight fall on a particular place? 5. If the sun is high overhead here in the middle of the day, what would you expect to be the situation on the other side of the Earth? 6. What part of Australia sees the sun first at the beginning of each day? 7. How many different times zones are there in the world? 8. How many different time zones are there in Australia? 9. Who came up with the idea of time zones and when was this? 10. What invention made it necessary for different places to have the same time? 11. In which country of the world is Greenwich? 12. What longitude would you expect to see given for Greenwich on a map? 13. What time would it be for astronauts out in space at this moment when they are constantly passing over many different time zones?

5 14. About how many degrees is the Earth s axis tilted from the vertical? Our Earth in Motion: 15. Which hemisphere is pointing towards the Sun in late December? 16. What season will this be in the northern hemisphere? 17. What two places on Earth can experience 24 hours of daylight in summer and 24 hours of darkness in winter? 18. When is the winter solstice in Australia? 19. What is the name of the line drawn to show the most southerly distance the sun can reach from the equator in June? 20. In which months do the two equinoxes occur? 21. What two seasons do we have when it is an equinox? 22. What is the shape of the moon s orbit around the Earth? 23. How many days does it take the moon to complete one orbit? 24. What phase of the moon do we have when the moon is on the opposite side of the Earth to the sun? 25. How many days are there between a full moon and a new moon?

6 Our Earth in Motion: 26. When we have had a new moon and so the moon appears to get bigger every day, do we say that the moon is waxing or waning? 27. The force that pulls on the oceans to form the tides is called a pull. 28. How many high tides does each place have in one day? 29. The high tides that are experienced when both the Sun and Moon are on the same side as the earth are called tides. 30. What do people living on the coast see when it is a neap tide?

7 After the Program Our Earth in Motion: 1. Wordsearch: The letters that remain, once you have found all the words below, spell out a sentence if written down in the order they are listed from top to bottom. ANTARCTIC ARCTIC AUTUMN AXIS DARKNESS DAYLIGHT EARTH EQUATOR EQUINOX GRAVITATIONAL GREENWICH HEMISPHERE ILLUMINATION LATITUDE LONGITUDE MOON NEAP PHASE REVOLVE ROTATE SEASON SOLSTICE SPRING SUMMER SUN TIDES TILT TIMEZONE WANING WAXING WINTER G R E E N W I C H R E M M U S T R H N O I T A N I M U L L I E W A N I N G E N O Z E M I T V A E V L O V E R I N U S E I A X I S I W E T H G I L Y A D E I N M U T U A F R O H W S E D N M E A P A E N A E I E A S U G S T R T D T P M N A N P S T H O T I U S H I T S T R E E I R L L T N A S E O A I O Q N G T S I D S P R N R N I U U K N F T T E H N F C G I A C I R O A I U E O L T T T T T L N A L O C R O U I N D O I E R O D S T E M A C H T R A E C N X D Hidden Sentence:

8 Our Earth in Motion: 2. Student-created Crossword: Instructions to student: Write meanings for any 10 words listed above, then make them into an interlocking crossword where your meanings become the clues. Swap with a friend and see if you can solve each other s puzzles. 3. Expert Groups: Instruction to teacher Divide the class into 5 equally sized groups (5 groups of 5 students is ideal) Give each group one of the topics listed below to become very familiar with, so that they can teach the principle to others. Topics: Day & night Time zones Seasons Phases of the Moon Tides Each group should spend minutes preparing some basic notes and selecting suitable balls, which the teacher has provided, to represent the Earth and Moon, and a torch or other light source to represent the sun. After minutes the groups should break up and form new groups so that each group has someone in it who has become an expert in that topic. This could be done in a second lesson. The experts now in turn teach the new group what they have learnt in their original group. If each expert takes about 10 minutes to teach their topic, then this part of the lesson will take about 50 minutes. If the class is smaller than 25, the first two topics could be combined creating only 4 topics. If one group has more than 4 people, it could be organized so that in these groups two students share the first large topic and break it into two as written above.

9 Suggested Student Responses During the Program Our Earth in Motion: 1. Exactly how long does it take for the Earth to spin once on its axis? 23 hrs 56 mins 2. The axis is an imaginary line that passes through which two points on the Earth? North and south poles 3. How long exactly does it take the Earth to revolve around the Sun once? 365¼ days 4. What do we call the time when the Earth rotates and the first rays of sunlight fall on a particular place? Sunrise 5. If the sun is high overhead here in the middle of the day, what would you expect to be the situation on the other side of the Earth? Night time, darkness or midnight 6. What part of Australia sees the sun first at the beginning of each day? East coast 7. How many different times zones are there in the world? How many different time zones are there in Australia? 3 9. Who came up with the idea of time zones and when was this? Canadian Sir Sanford Fleming in What invention made it necessary for different places to have the same time? Railways 11. In which country of the world is Greenwich? England 12. What longitude would you expect to see given for Greenwich on a map? What time would it be for astronauts out in space at this moment when they are constantly passing over many different time zones? Greenwich Mean Time (GMT) 14. About how many degrees is the Earth s axis tilted from the vertical? Which hemisphere is pointing towards the Sun in late December? Southern 16. What season will this be in the northern hemisphere? Winter

10 Our Earth in Motion: 17. What two places on Earth can experience 24 hours of daylight in summer and 24 hours of darkness in winter? Places inside the Artic and Antarctic circles 18. When is the winter solstice in Australia? June What is the name of the line drawn to show the most southerly distance the sun can reach from the equator in June? Tropic of Capricorn 20. In which months do the two equinoxes occur? March and September 21. What two seasons do we have when it is an equinox? Spring and autumn 22. What is the shape of the moon s orbit around the Earth? Ellipse or oval shape 23. How many days does it take the moon to complete one orbit? What phase of the moon do we have when the moon is on the opposite side of the Earth to the sun? Full moon 25. How many days are there between a full moon and a new moon? When we have had a new moon and so the moon appears to get bigger every day, do we say that the moon is waxing or waning? Waxing 27. The force that pulls on the oceans to form the tides is called a gravitational pull. 28. How many high tides does each place have in one day? The high tides that are experienced when both the Sun and Moon are on the same side as the earth are called spring tides. 30. What do people living on the coast see when it is a neap tide? A smaller difference in heights between high and low tides

11 After the Program Our Earth in Motion: 4. Wordsearch: The letters that remain, once you have found all the words below, spell out a sentence if written down in the order they are listed from top to bottom. G R E E N W I C H R E M M U S T R H N O I T A N I M U L L I E W A N I N G E N O Z E M I T V A E V L O V E R I N U S E I A X I S I W E T H G I L Y A D E I N M U T U A F R O H W S E D N M E A P A E N A E I E A S U G S T R T D T P M N A N P S T H O T I U S H I T S T R E E I R L L T N A S E O A I O Q N G T S I D S P R N R N I U U K N F T T E H N F C G I A C I R O A I U E O L T T T T T L N A L O C R O U I N D O I E R O D S T E M A C H T R A E C N X D Hidden Sentence: _T H E V I E W F R O M E A R T H I S N O T D I F F I C U L _T T O U N D E R S T A N D_