The movement of Sun and the Earth

The Sun and the Earth

Chapter Notes:

This chapter focuses on the relationship between the sun and the earth, it is a key chapter in Geography.

It relates to the, ‘God with No Hands Story; rocks, water, air, solids, liquids, gasses, today as it was yesterday and millions of years ago, the laws are obeyed in the same way, the world spins around and around itself and around and around the sun’.

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The Two Movements of the Earth and the Rotation Work

Material Description:

Tennis ball on a string, Charts 7a to 10a, globe, stationary lamp

Method:

Say, ‘The Earth with all the people, plants and animals is turning around and around the Sun, like this’.

Demonstration; Spin the tennis ball on a swing around your head

Say, ‘Now the Earth not only dances around the Sun, it is so happy to be born that it dances around and around itself something like this’.

Twirl

Say, ‘It has done this from the beginning and it still does it today.  I wonder what would happen if the Earth did not spin.  Remember last summer, think of the hottest day, it was very hot’.

Demonstration; Show Chart 7a

Say, ‘The Sun radiates heat from all it’s surfaces in all directions, the Earth only receives a very little part of it, some people think that the Earth only receives a two-billionths of the sun’s heat, can you imagine getting all of that heat, what would happen if the earth did not rotate?  On one side of the earth the people, the plants and the animals would all burn up and on the other side they would all freeze’.

Chart 8a

Demonstration; using a globe and a stationary lamp, say, ‘The Sun can only light up one part of the earth at a time, the part facing it.  Turn on the lamp, ‘We know the Earth moves around the Sun’.  Rotate the globe from west to east, say, ‘here we see the Earth coming into the light and here we see some of the Earth going into the dark’. We know that the Earth rotates around itself and it is happening all the time, we know this as day and night’. Pick a country and, while rotating comment on it’s movement  in and out of the lights say, ‘We can see that Germany has gone into the dark, now we see it coming into the light, now we have dawn, it moves further into the light, giving us noon or midday, now it moves towards the end of the light, we have sunset, then midnight, then dawn, noon, sunset, midnight.  So in some parts of the Earth it is dawn, in another place it is midday, in another place sunset and in other places it is midnight’.  Point at a variety of places while doing this.  ‘The Sun doesn’t actually move, we just think it does, it is a bit like travelling on a train, it looks like the trees and the houses and the fields are flying past, but really it is us that is moving.  We have the same impression that the sun is moving when really but is the Earth that is moving.’

Lets have a look in more detail’.

Show Chart 9a

Say, ‘Here we have light and here we have darkness, here we have dawn and the sun seems to move higher in the sky till at noon we have midday, at midday the sun is directly over head.  Then the Sun seems to sink in the sky and we have sunset, we can’t see the sun any more, but we have midnight and then the sun looks like it rises and we have dawn again’.  Continue to describe the cycle.  ‘We know that really it is the Earth that moves, at some point it is dawn, at a place on the other side of the earth it is opposite, it is sunset.  At another place it is midday and at a place on the earth opposite it is midnight. This happens because the Earth is a sphere. The complete movement takes twenty-four hours to happen and if it were equally divided we would have twelve hours of light and twelve hours of darkness.  If you live on the centre of the Earth this is what happens’.

Chart 10a

‘Supposing we say that the Sun rises in the east at six o’clock in the morning, it climbs higher in the sky till at noon we have 12.00, and then it begins to sink in the west, until at 6.00pm we have night, then we would have midnight and then dawn again and noon and sunset in the west and midnight again.  My question is, “What is the hottest and coldest hour?” We think that at 2.00 in the afternoon because there is an accumulation of heat, and just before the dawn it is the coldest because that part of the Earth has been without heat for so long.’

You may experiment with magnifying glass and paper can be done here with responsible children.

Notes:

This work presents the two movements of the Earth and their consequences with demonstrations, appealing to the imagination and intellect.

  • Rotation – movement of the Earth around itself
  • Revolution – the movement of the earth around the sun

The arrows on 9a and 10a represent the apparent movement of the sun

When to give the lesson:

Aspects of this chapter are picked up with small groups of children, parallel to the chapter, ‘Examining the Nature of the Elements’ and early work on the Features of The Earth’.

After the lesson:

The children can repeat the demonstrations with globe and lamp.

The children can look at the charts and ask questions

Follow up work:

Presentation of A.M. and P.M. can be done here.

 The presentation of A.M. and P.M.

Material Description:

none

Method:

Say, ‘We talked about the idea of the Sun, seeming to move higher and higher until it reaches it’s highest point, this highest point is called meridian, which comes from the Latin, ‘meridias’, this highest point or zenith is at 12 o’clock or midday, this time before 12 o’clock is called antemeridian, the time after is called postmeridian.  It was very difficult for people to day “I will see you at ten antemeridian, so they said, I’ll see you at 10 A.M.’

When to give the lesson:

After ‘The Two Movements of the Earth’

After the lesson:

Encourage the children to write times, A.M. and P.M. and associate their everyday lives, organising events into A.M. or P.M.

Children can also use timetables and notices with A.M. and P.M.

Time Zones

Material Description:

Chart W1, 12 white strips and 12 black strips, the same length as the chart, 12 red clocks and 12 black clocks, globe on a stand

Method:

Say, ‘We have been talking about the idea that the Earth is a sphere’

Introduce the Chart W1, clipped into a cylinder, say, ‘Because we want to use this chart I will lay it out flat’,

Let’s look at our globe, say, ‘We were talking about the Sun apparently rising in the East and climbing higher in the sky, until at twelve o’clock midday when it is at it’s highest point, and then it seems to sink lower in the sky until it sets in the West’.

Take a white strip and place it from the North Pole down the centre to the South Pole, saying, ‘Let me take a strip of paper to present this to you’. Take a strip of paper and place it on the globe down the longitude, ‘Lets suppose that all the pieces down this line have the same time.  I have white strips, black strips and some clocks’. Put out the clock’s in order, while laying them name them by there times, beginning with red clocks at 7 o’clock till six o’clock.  Say, ‘These strips are going to represent day (white) and these night (black) these clocks are for the day (red clocks) and these clocks night (black clocks).

‘In the morning in Ireland it is 9.00’, place a while strip over Ireland.  ‘I have a friend in Chennai, India, I want to know time it is, for each section east it is an hour earlier’.  Place the strip to the right of the first strip and say, ‘It is ten o’clock,’ Place a red clock and keep moving the strip to the East and say the local time until India is covered, placing the red clocks.  Keep asking, ‘Have I got to India yet?’ When you have notice you are not yet in Chennai and keep moving, conclude, reading the clocks, saying, ‘When it is nine o’clock in Ireland it is three o’clock in Chennai’.  

Now show the strips going west, placing a dark strip if the child thinks it will be dark and calculate the local time.

Then demonstrate moving from one end of the chart to the other.

When the children express curiosity about the meridian, tell them about Greenwich Meantime, the prime meridian of zero degrees longitude, this represents standard time for that section of longitude.  It follows an agreement between many countries in 1884 that led to standard time.  Each timezone is an area of the Earth which runs from North to South but is not very wide East to West.  In twenty-four hours the Earth turns in one complete circle of three-hundred and sixty degrees three hundred and sixty divided by twenty-four is fifteen, so the Sun appears to move by 15 degrees of longitude every hour.  Each zone has a time one hour earlier than the zone to the East, in the same zone all places keep the same time, all the places with the same degree of longitude have midday at the same time.  The time zones are numbered from Greenwich in England and there are twelve zones to the East and twelve zones to the West.  Greenwich meantime fixes the time for places all over the world, the reason that Great Britain was chosen at that time, rather than France and The United States was because the British had the biggest navy.

Notes:

For the first presentation go either East or West, beginning in your country.

The children can decide whether or not to use the black strips, depending on whether or not they think it would be dark, this brings up a discussion about the seasons.

Introduction to the Zones

Material Description:

Flat bar of plasticine and sphere of plasticine, both with cocktail sticks stuck in, Charts 11a, 12a, 14a black piece of paper, a piece of chalk and a torch, lamp, knitting needle.

Method:

Say, ‘We saw during the day, that when the Sun is directly overhead the Sun’s rays fall perpendicularly on the Earth, but there are areas of the Earth where this can never happen.  I wonder why this is’

‘If we look at our little ball here, our little sphere we can see that we have only one stick with an angle of ninety degrees, the others are a little different, they are oblique.

On the bar all the angles are at ninety degrees, if the Earth was like this the Sun’s rays would hit the Earth at ninety degrees, but actually the Earth is a sphere.

Where the Sun’s rays shine perpendicularly, at a right angle, it is very hot.  Where they fall obliquely the heat is spread over a larger area.

Show Chart 11a

Demonstrate shine the torch directly over the black paper and ask a volunteer to make with chalk the area where the light hits, then shine the torch at an angle which increases the area where the beam would hit and draw round the larger shape.

Say, ‘We notice that the area is larger where the light fell obliquely’

Show Chart 12a.

Count the rays from a perpendicular and oblique source. Say, ‘It takes half the amount of rays to cover the same area, there is twice as many rays for the same surface when the source is perpendicular, so it is easy to see why the perpendicular rays make it hotter.’

Show Chart 14a

Say, ‘Just look at how much atmosphere they both have to travel through! This is another reason why the perpendicular one gives more heat, the oblique ray looses more heat to dust and particles in the atmosphere, while the perpendicular one goes straight through.’

Using this globe and lamp I want to talk about certain imaginary lines, ‘If I could draw an imaginary line around the surface of the Earth, beyond which the rays never fall perpendicularly it would be approximately around here, we call it the ‘Tropic of Cancer’. Place a knitting needle so that it’s shadow falls over the Tropic.  ‘Beyond this line the rays off the Sun never fall perpendicularly.  To the South, if we draw an imaginary line beyond which the rays of the Sun never fall perpendicularly we have whet we call the ‘Tropic of Capricorn’. Place a knitting needle so that it’s shadow falls over the Tropic. ‘and exactly half way in between we have another imaginary line which we call the ‘Equator’, between these two imaginary lines, the ‘Tropic of Cancer’ in the North and the ‘Tropic of Capricorn’ in the South, the rays of the Sun always fall perpendicularly.  This is why between these two imaginary lines we always find the hottest parts of the Earth.’

Notes:

We introduce the idea that the sun’s rays fall perpendicularly and obliquely on the Earth.  This heats the world in different ways resulting in different climatic zones.  This maybe a spontaneous realisation following the work on day and night.

We give some of the elements of the sun and the earth in isolation and allow the children to make a synthesis over time.  We have now introduced rotation – which result in day and night, light and dark, resulting in the convention of AM and PM.  The natural phenomena of perpendicular and oblique rays result in an uneven hearing of the Earth’s temperature, which leads to an understanding of the climatic zones of the Earth.

Working Charts; The Zones

Material Description:

Show Chart 18a and the pieces

Method:

Children identify where they live, their hemisphere, zone, to notice the imaginary lines and other zones.

Go through the whole cycle oncepastedGraphic.pdf

Say, ‘What we are going to look at today is the Seasons,’ While talking place the Sun piece to the left on the appropriate imaginary line. ‘If the Sun is overhead at the Tropic of Cancer, what season will it be for us?’ (Summer) ‘So what date will it be?’ (21st June). Place the date on the right side of the appropriate line.  ‘We know that it is the Earth that is moving not the Sun, let’s keep that in mind.  The Earth has moved so now the Sun is overhead at the Equator, what date is it now?’ (22nd September) Take away the date and put the new date on the appropriate imaginary line at the opposite side of the sun. ‘Now the Sun is overhead at Tropic of Capricorn. What season is it for us?’ (Winter) ‘What is the date?’ (22nd December) ‘Now the Sun is overhead at the Equator, what is the Season for us?’ (Spring) ‘So what is the date?’ (21st March).

Ask the child questions at random

The date is the 22nd December, place the date.  Where is the sun?

It is Summer for us.  Where would the Sun be?  What would the date be?

When children are very confident encourage them to work out the dates with reference to the southern hemisphere.

The children explore their own hemisphere

Finally they explore the other hemisphere

When to give the lesson:

This work is given parallel to other work with the Sun and the Earth

Show Working chart 3

Material Description:

The protractor chart W3 (shows latitude) and 4, an atlas, notation paper and pencil.

The protractor chart is a large circle divided into sectors, two blue representing the temperate zones, two white for the frigid zones and two red for the Tropics and a yellow arrow which does not move.  A moving protractor part which is divided between 0 degrees at the Equator and 90 degrees at the Poles.  The imaginary lines are highlighted.

Method:

Introduce the chart to the children,

Say, ‘Here we have the protractor chart, you can see it begins at 0 degrees and goes up in multiples of 10 to 90.  We have 0 degrees in red is the Equator.  This line here is the Tropic of Cancer, remember it is the northerly limit of where the suns rays can shine perpendicularly, this is the Tropic of Capricorn, the most southerly limit of the Sun’s perpendicular line.  Here is the Arctic Circle and here is the Antarctic Circle.  Review the degrees which the children are familiar with from Chart 18a, 23.5 degrees for the tropics and 66.5 degrees for the Arctic and Antarctic circles.  We have two blue for the temperate regions, the two red for the very hot the two while for the very cold.’  

Review the seasons in one hemisphere;

‘If the Sun is on the Equator, what Season would it be for us?’  Move the protractor so it points to the Equator? (Spring/Autumn)

‘If it is overhead at the Tropic of Cancer what season is it for us?’ Move the semi-circle (Summer)

‘If it is overhead at the Tropic of Capricorn what season is it for us?’ Move the semi-circle (Winter)

Introducing the atlas

The children explore a familiar place first, say, ‘We are living in Dublin we want to find out where we live, we use the index at the back, it has all the cities in alphabetical order.  Write down the page numbers and co-ordinates on a piece of paper.  Find the page, say, ‘It is like the tables memorisation boards’, go down and the across.  Find the city and then write down the exact co-ordinates.

Say, ‘We can use our chart to find out something else, we said it was fifty degrees North’. Here show you are checking the hemispheres. Place a piece of blue tack on the board at 50 degrees on the side with the arrow, ‘Suppose the Sun is overhead at the Tropic of Cancer, what Season is it for us?  Slide the semi circle so that the yellow arrow lines up the with Tropic of Cancer and compare where the blu tac is in relation to the colour under the semi circle. ‘Now let’s look, the blue parts are for the not very hot, not very cold pasts, is that true of?’ (yes)  ‘If the Sun is directly overhead at the Tropic of Capricorn what season is it for us?’ (Winter). Look to see the colour beneath the semi circle.  ‘We are now into the cold zone, but does it get very cold?’ (not very) say, ‘I wonder why that is’. This makes a connection to the gulf stream.  ‘Supposing it is spring’, move the semi-circle, ‘we are back into the not very cold, not very hot, is this true?’ (yes)

Now work with another place which has significance for the child if possible which will give some contrast, if possible ask the child to verify if the conditions shown on the lower half of the grid are accurate.

Key:

Opens up the children to explore local weather conditions that cause deviation from the most basic model

Aim:

Synthesis of knowledge relating to the seasons and latitude

Notes:

This work provides an opportunity for children to use their hands and intellect, to reason about the seasons.

The children do not need to have memorised the dates.

The chart is a starting point which connects the seasons to the hemisphere, the child will discover more about the gulf stream and why local weather conditions, like wet summers occur with the work on air and water.

Using the atlas introduces the idea of looking for latitude and checking if it is in the Northern or Southern hemisphere.

Show Working chart 4

Material Description:

Working chart 4, loose pieces for the sun and significant dates, coloured strips

  • very bright red for very hot Summer
  • red for hot Summer
  • pink for Arctic Summer
  • white for Winter
  • blue for very cold Winter
  • green for Spring
  • brown for Autumn

Method:

Introduce the chart to the children, systematically, beginning with your own hemisphere

Describe the chart indicating and naming the Equator, Tropics, Temperate Zones, Arctic and Antarctic Zones and the Torrid Zones (desert).  Introduce the meaning of the colours on the strip.

Choose a position for the Sun and begin in your zone ask the children questions, ‘Now the Sun is overhead at the Tropic of Cancer.  What is the season? What is the date?’ Place the pieces.  ‘We are living in the North Temperate Zone, so what kind of Summers do we have?’   Place the red strip over the place on the working chart that says ‘North Temperate’. ‘What do we know about the tropics?’ (very hot) Place the bright red strip. ‘And what about the Arctic?’ (Arctic Summer) Place the pink strip above.

‘In the Southern Hemisphere, what Season would it be?’ (Winter) ‘What do you think the Tropical Zone would be like?’ (hot), place the red strip. ‘What about the Temperate Zone?’ (Winter) place the white strip.  ‘What about the Antarctic circle?’ (very cold) place the blue strip

Children reason about the seasons and the climates in the different zones with Working chart 4.

Notes:

There is no control of error, it is an exercise based on reason, it should be used with older children.

Join the children when they are using this,it shouldn’t be used mechanically but with questions to join up their knowledge.

For places with other conditions e.. Monsoon, typhoon season adapt the seasons above.

After the lesson:

The children may wish to follow this up by learning about other zones and early explorers.

Solstices, Equinoxes and Seasons

Material Description:

Ball of wool and a knitting needle, globe, lamp, Charts 15a to 18a

Method:

Say, ‘In the olden days people thought the Sun moved and not the Earth, they noticed that it did not rise at the same point everyday.  In the Spring it seemed to rise a little more to the North each day, until it reached a turning point, which they called the Summer Solstice from the Latin ‘Sol’, Sun and ‘stice’ or ‘stare’, which means to stand still or be stationary because this was the day that the Sun stood still.  They also noticed that from the Winter Solstice the days grew longer and longer until the Summer Solstice when there was the longest day of all.  There are two Solstices, one in Summer and one in Winter and we know this to be true because in the Summer the days are longer, you can stay out and play longer.’

‘I am wondering why all this happens’

‘The Earth is not only moving round and round itself, it is spinning round and round the sun’.

Spin the ball of wool on the perpendicular knitting needle around while moving it anti-clockwise around the lamp.

‘But it is not really quite like that, it moves around with a tilt.’

Tilt the needle, either tilt the North towards or away from the Sun.

‘While the Earth is going around the Sun not all the Earth is being heated in the same way, when I do this I want you to watch where the light falls’

Move the globe to four points around the lamp, keeping the axis in the same direction, Saying, ‘Where is the light shining now,?’ (the South), ‘So it is Winter for us,’ move it more, ‘Where is it now?, So it is Spring’, move it more, say, ‘It is Summer’, move it more, ‘It is now Autumn’.

Because the Earth’s axis is tilted in a certain way there is not an even distribution of light

Repeat the demonstration a second and even third time emphasising where the light falls and the connection with the seasons.

‘Let’s have a look at this on a chart

Show Chart 15a

Say, ‘This shows the two Equinoxes which happen at Autumn and Spring.  Equinox is Latin, for ‘equs’ equal and ‘nox’ night.  Look at the Sun, it is directly overhead at the Equator for the Spring and Autumn Equinox.  When it is directly overhead at the Tropic of Cancer it is Summer for us and when it is directly overhead at the Tropic of Capricorn it is Winter for us’.

Show Chart 16a

Say, ‘When the Sun is directly overhead at the Tropic of Cancer it makes a special angle with the Equator, it makes an angle of 23 degrees, and when the Sun is directly overhead at the Tropic of Capricorn exactly the same thing happens, there is an angle of 23 degrees.’

Show Chart 17a

‘The journey around the Sun takes a year, the path the Earth takes around the Sun is called the orbit, as the Earth travels round the orbit, parts of the Earth fall perpendicularly under the Sun’s rays, the most northerly limit where the Sun’s rays shine perpendicularly is the Tropic of Cancer and the most southernly limit is the tropic of Capricorn.’  Remember the imaginary line we have it between, it is the Equator.’

‘You can also see that on the chart we have some dates, when the Sun is directly overhead at the Tropic of Cancer it is June 21st, that is Summer for us.  The Earth continues on it’s journey and now the Sun is directly overhead at the equator and it is now September 22nd, so it is Autumn for us, the Sun continues on it’s journey and it is now directly overhead at the Tropic of Capricorn, it is December 22nd and it is Winter for us.  The Earth continues on it’s journey and now it is directly overhead at the Equator, it is March 21st and it its Spring for us, the Sun continues on it’s journey until it is directly overhead at the Tropic of Cancer and it is now  Summer again, for us.’

Notes:

When the children work with atlases they realise what 23 degrees means, it relates to the angle that the rays of the sun

Chart 15a – seasons in the northern hemisphere, the children will wonder about the seasons in the southern hemisphere, when the sun is directly overhead at the Tropic of Capricorn it is Summer in the southern hemisphere.

Chart 16a is important for latitude

Chart 17a puts all of the ideas together on one map, here we concentrate on the key ideas which the children keep coming back to.  The imaginary lines are created because of the relationship between the Sun and the Earth.

After the lesson:

After the children have worked with the Seasons we introduce the idea of The Zones.

Show Chart 18,

Say ‘Here around the middle of the Earth we have the hot zone, we call it the Torrid Zone from the Latin ‘toridas’ which means dried up or parched.  Near the poles we have another zone, the Frigid Zone, which comes from the Latin, ‘frigidus’ meaning cold, the Arctic Circle marks the limit where, at least once a year the sun never sets. Between the Arctic Circle and the Tropic of Cancer we have a Temperate Zone, which comes from the Latin, ‘temperatus’ meaning neither hot nor cold, and this is where we live’.

After the lesson:

There is a lot of information on this chart, do not overload the children with information, just let then see that there are different zones and etymology.  Leave it out and let the children ask there own questions.  The children might be interested in studying the Arctic, Antarctic and Equator and the explorers, so will need access to research materials.

Notes:

The second movement of the Earth is revolution it takes approximately 365 and 1/4 days combined with the one complete revolution.  The revolution of the Earth around the Sun and the tilt of the axis to 23 degrees cause;

  • Changes in the altitude of the midday sun at different times of the years
  • Fix the tropic, and arctic and Antarctic circles.
  • Cause the changes of the Seasons
  • Causes the variation between the lengths of time spent in night and day.

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