science education teaching booklet

Name:________ Our Solar System The sun is the centre of the system of heavenly bodies that is called the solar system. The Earth is one of nine planets that revolve around the sun. These nine planets travel around the sun in an almost circular path called an orbit. The orbits are in the shape of an ellipse but some are more circular than others. An ellipse is a slightly flattened circular shape. The orbit of Pluto is tilted and less circular in comparison to the orbits of the other planets. At most times, Pluto is the furthest planet from the sun. However, because of the more flattened shape of its orbit, Pluto was closer to the sun than Neptune between 1979 and 1999- In 1999, Pluto is once again the most distant planet. Light from the sun is reflected off the planets allowing us to see them. The planets Mercury, Venus, Mars, Jupiter and Saturn can all be seen without using a telescope and were discovered in ancient times. They were noticed amongst the many stars n the sky because they moved in regular patterns against the background of stars. In fact, the word 'planet' comes from a Greek word meaning 'wanderer'. The most distant planets, however, cannot be seen without telescopes and were discovered more recently. William and Caroline Herschel discovered Uranus accidentally with a telescope in 1781. Le Verrier discovered Neptune in 1846 and Pluto was first photographed in 1930. Materials Experiment THE SCALE OF THE SOLAR SYSTEM 1. Cardboard 2. Colour pens 3. Trundle wheel 4. Nine-planet sheet (see book) 5. Basketball 6. Scissors 1. Collect a basketball to represent the sun, 2. Colour and glue the nine planets sheet onto the cardboard and once dry cut each planet out neatly 3. One student should be selected to hold the 'sun' and its label. Nine groups of students should also be selected to carry the 'planets' and their labels to the correct distances from the sun. Method A Model of the solar system Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Distance from the 'sun' (metres) 1.5 2.7 3.7 5.7 20 36 72 110 150 (The model created here is not quite to scale. The distances from the 'sun' to the 'planets' listed in the table are one-tenth of what they need to be to produce a scale model.) 2 1.Describe your model in words. Does it surprise you in any way? ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ Label the Solar System Diagram Read the definitions, then label the diagram below. Definitions Sun - The Sun is a star at the centre of our Solar System. Mercury - Mercury is the planet closest to the Sun. Jupiter - Jupiter is the fifth planet from the Sun. This gas giant is the largest planet. Saturn - Saturn is the sixth planet from the Sun. This gas giant has large, beautiful rings. Venus - Venus is the second planet Uranus - Uranus is a gas giant and is the seventh from the Sun. It is the hottest planet. planet from the Sun. Earth - Earth is the third planet from the Sun and the planet we live on. Mars - Mars is a red planet and the fourth planet from the Sun. Neptune - Neptune is a gas giant and is usually the eighth planet from the Sun. Pluto - Pluto is a rocky planet that is usually the farthest planet from the Sun. It is the smallest planet. Read this passage and then answer the questions below. 3 For over 2000 years there has been a variety of ideas concerning the organisation of our solar system. It all began in approximately 600 B.C. with Thales who proposed the idea that the Earth was a disc floating on water. Around 500 B.C. Pythagoras then proposed that the Earth was at the centre with all the stars in orbit around it. This model was called the geocentric model and it was accepted by the rulers of Ancient Greece. Some 300 years later Aristarchus proposed that the Sun was at the centre with the Earth in orbit around it. This was called the heliocentric model but it was rejected as be bad no experimental support. In 120 AD Ptolemy proposed an updated geocentric model where the Sun circled the Earth and the other planets circled the Sun. Things then became fairly quiet until the sixteenth century when Copernicus provided experimental support for the heliocentric model. However be did not publish his results until close to his death as they would have challenged the beliefs of the authorities and the church. Galileo then took up on Copernicus' ideas and using a telescope be discovered four moons going around Jupiter that provided evidence for the heliocentric model. Again the church was not impressed and be was jailed for life. Finally Isaac Newton with his theory of gravity and knowledge of the ideas of Galileo proved that Copernicus was correct after all. 1. What is the geocentric model and who was the first to propose it? ___________________________________________________________________________ ___________________________________________________________________________ 2. What is the heliocentric model and who was the first to propose it? ___________________________________________________________________________ ___________________________________________________________________________ 3. Why was the heliocentric model rejected? ___________________________________________________________________________ ___________________________________________________________________________ 4. What did Ptolemy propose in 120 A.D. ___________________________________________________________________________ ___________________________________________________________________________ 5. Copernicus provided experimental support for the heliocentric model. Why did he not publish his results until close to his death? ___________________________________________________________________________ ___________________________________________________________________________ 6. How did Galileo provide evidence for the heliocentric model? ___________________________________________________________________________ ___________________________________________________________________________ 7. Who finally proved that the heliocentric model was correct after all? ___________________________________________________________________________ ___________________________________________________________________________ 4 A closer look at the planets Eight of the planets fall into two distinct groups: 1. The terrestrial planets are those that are similar to Earth. They are small and solid. Mercury, Venus, Earth and Mars are terrestrial planets. 2. The larger, outer planets are referred to as the gas giants. Jupiter, Saturn, Uranus and Neptune fall into this group. These huge planets do not have a solid surface. Pluto is in neither group. It is not similar to Earth. In fact it is smaller than our own moon. Unlike the gas giants, its surface is frozen solid. All of the planets spin, or rotate, on their axes as they orbit the sun. The Earth rotates once every 24 hours. This period is called one day. Jupiter takes only about 10 hours to rotate. That means that a day on Jupiter would be only 10 hours long. The planet Venus takes 243 Earth days to complete one full rotation. Information about the planets Average distance from the sun (million km) 57.9 108.2 149.5 227.9 778.3 1427 2870 4497 5900 Time to orbit the Sun 88 days 225 days 365 days 1.9 years 11.9 years 29.5 years 84 years 165 years 248 years Mass compared with the Earth (=1) 0.06 0.82 1 0.11 318 95 14.6 17.2 0.002 Main gases in atmosphere Temperature on surface Number of moons 0 0 1 2 16 18 15 8 1 Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto None Carbon dioxide Nitrogen & oxygen Carbon dioxide Hydrogen & helium Hydrogen & helium Hydrogen, helium & methane Hydrogen, helium & methane Methane 350°C to -17O°C 450°C to over 1000°C -90°C to 50°C Av -23°C Av -150°C Av -190°C Av -210°C Av -220°C Av -230°C Activities 1. Complete the following sentences. a. Mercury, Venus, Earth and Mars form the ___________________ planets. b. Gases in a planet's atmosphere are held to it by _________________. c. The surfaces of the inner planets are made of ___________________. d. The sizes of the outer planets are generally _____________ than those of the inner planets. 5 The table below shows how the size and distance from the sun of other planets compare with Earth. How the other planets compare with Earth Planet Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto Diameter at equator (Earth = 1 unit) 0.38 0.95 1.00 0.53 11.2 9.41 3.98 3.81 0.24 Average distance from the sun (Earth = 1 unit) 0.39 0.72 1.00 1.52 5.19 9.43 19.1 29.9 39.3 2. Follow the instructions below to produce two scale drawings of the solar system. The first drawing will show how the sizes of the planets compare with each other. The second drawing will show how far the planets are from the sun. (a)On a sheet of A3 paper, draw a circle to represent the size of each of the nine planets. Use the diameter in Earth units from the table above and a scale of 1 cm = 1 Earth unit. Colour and label each planet. (b)Turn the sheet over and rule a 40cm line. At the left end of the line, draw a large dot and label it as the sun. Use the distances in Earth units from the table to draw a dot representing each planet on your line. Again, use a scale of 1 cm = 1 Earth unit. Label each planet. 3. Which planet is closest in size to the Earth? ___________________________________________________________________________ ___________________________________________________________________________ 4. Do the planets appear to fall into groupings, either in size or in distance from the sun? ___________________________________________________________________________ ___________________________________________________________________________ 5. Why is it not possible to represent both the size and the distance from the sun on the same diagram? ___________________________________________________________________________ ___________________________________________________________________________ 6. How long does it take the Earth to complete one full rotation? How does this compare with Jupiter and Venus? ___________________________________________________________________________ ___________________________________________________________________________ 6 Statement a. Mars is closer to the sun than the Earth. b. Saturn is positioned between Jupiter and Uranus. c. The average temperature on Neptune is lower than that on Saturn. d. The atmosphere on Venus contains hydrogen and methane. e. Venus is larger than Mercury but is smaller than Neptune. f. Uranus is closer to the sun than Jupiter, but is further away than Neptune. True/False g. Mars takes about twice as long as Earth to travel around the sun. 7. Decide which of the statements is true and which are false. 8. Why would it be difficult to land a spacecraft on Jupiter ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ ___________________________________________________________________________ The bar chart shows the time taken by five planets A, B, C, D and E in the solar system to complete one rotation. 1. Which planet is Earth? Explain your answer. ______________________ 2. Neptune takes two-thirds as long as the Earth to complete & one rotation. Which planet is Neptune? _______________ 3. Uranus takes 1 hour longer than Jupiter to complete one rotation. Which planets are Uranus and Jupiter?_______________ 7 The Night Sky When we look at the night sky, we see mainly stars. There are billions (1 billion = 1000 million) of stars in the Universe, grouped together in great spinning star clusters called galaxies. Most of the stars we see belong to our home galaxy, the Milky Way. The Milky Way is one of perhaps 100 billion galaxies in the Universe. Each galaxy contains billions of stars, as well as gases, dust clouds and planets. There are about 20 galaxies near us. The Milky Way and the Andromeda galaxy are the two biggest members of a small cluster of galaxies in our neighbourhood in space, called the Local Group. Earth is located in the Milky Way galaxy. Almost every point of light you can see around you at night is also in the Milky Way galaxy, except for a few other nearby galaxies. People in the Southern Hemisphere can see two galaxies, the Large and Small Magellanic Clouds. These appear as small smudges of light, like faint clouds. People in the Northern Hemisphere can see the Andromeda galaxy. Constellations Small star groups that form patterns, called constellations, are easily seen in the sky. If you have seen the 'saucepan' in the sky, then you have seen part of the constellation Orion. Astronomers have named over 90 different constellations. Constellations are important in a study of space since they help to form a map of the sky. Any location in the sky can be described in relation to the position of a known constellation. Twelve special constellations are known as the constellations of the Zodiac. The Sun appears to occupy a different constellation each month. Did you know? Light travels at the fastest speed we know: the speed of light is 300 000 km/s. Astronomers use light-years to help us understand the huge distances between objects in space. Knowing the speed of light, you can calculate that light travels about 10 million million kilometres in a year. This distance is called a light-year. Lets build a Telescope It is possible to build a simple telescope to observe the Sun, the Moon, and even the moons of Jupiter. WHAT YOU NEED Cardboard tubes, cardboard, convex lens (about 5 cm diameter and 50 cm focal length), convex lens (about 1.25 cm diameter and 2.5 cm focal length), foam blocks, plasticine or Blue-tac WHAT YOU DO Using the figure below as a guide, build and test your refracting telescope. After testing it, improve on your design if you can. CAUTION: Never look directly at the Sun, it will damage your eyes. 8 What else is out there? The Universe also contains clouds of gas and dust called nebulae, black holes, objects so dense that not even light can escape their gravitational pull, quasars, puzzling sources of intense radiation, and pulsars. Many cultures have legends or stories about how constellations formed. For example, the ancient Greeks told the legend of Orion the hunter and Taurus the bull. Imagine that you are an elder in an ancient civilisation and you are telling the children the legend about the formation of a constellation. Your legend should have a message that the children will remember when they look up into the sky and see your constellation. Use the following plan to create your constellation and its legend. Name and draw your imaginary constellation. Write the legend recounting the sequence of events that led to the formation of your constellation. Conclude your legend with the message that you want the children to remember every time they see the constellation. 9 Earths Little Companion The Moon orbits around the Earth once every 28 days. It always keeps the same side facing towards the Earth. Until 1959, when a spacecraft orbited the Moon, no one had ever seen the far side. The Moon does not produce any light of its own. We can see the Moon because light from the Sun is reflected from its surface. In the daytime, this reflected light does not seem very bright, and we may not even notice the Moon. But at night, although the light from the Moon is no brighter, it seems much more obvious in comparison with the dark night sky. The Sunlights up half of the Moon at any one time. If the Moon is almost between the Sun and the Earth, the Sun's light is shining on the far side of the Moon. The side nearest to us gets no sunlight. So we see nothing at all, or perhaps just the edge of the Moon catching the Sun. We call this New moon. As the Moon continues around the Earth, it reaches where all the sunlight side is facing us. We see the whole face of the brightly lit by the Sun. This is a full moon. Over a period of 28 days, our view of the Moon gradually changes. We see first a new moon, then a crescent moon, then a full moon, then a crescent moon. These charges are called the phases of the Moon Phases of the moon WHAT YOU DO Work with a partner. You will need a basketball, overhead projector, notebook, pencil, and darkened room. PERSON A You are the Earth. Sit in the centre of a darkened room, with a notebook and pencil. You 10 will draw the shape of the lighted part of the basketball as your partner stops every 45 degrees. PERSON B You are the Moon. Stand about a metre away from the Earth. Hold a basketball above your head. Turn on an overhead projector so that it shines towards you and your partner. Walk slowly round your partner, always facing them, anticlockwise. Stop every 45 degrees so that your partner can draw the lit shape of the ball as it revolves. Swap places with your partner and compare diagrams. DISCUSSION 1. Where was the ball when you saw a full moon? ___________________________________________________________________________ ___________________________________________________________________________ 2. Where was the ball when you saw a new moon? ___________________________________________________________________________ ___________________________________________________________________________ 3. When did you see the waxing of the Moon? ___________________________________________________________________________ ___________________________________________________________________________ 4. When did you see the waning of the Moon? ___________________________________________________________________________ ___________________________________________________________________________ Read the definitions, then label the moon phases diagram below. Label the Moon Phases Diagram Definitions Crescent Moon - when we can see only a sliver of the moon's disk (the side of the moon facing us) Full Moon - when the moon's disk is light because the Earth is between the sun and the moon Gibbous Moon - when we can see roughly three-quarters of the moon's disk Half Moon - (also called quarter moon) New Moon - when the moon's disk is dark (and invisible to us) because the moon is between the sun and the Earth Quarter Moon - (also called half moon) when we can see one half of the moon's disk (this is one-quarter of the entire moon's surface) Waning Moon - when the moon seems to be getting smaller, going from full to gibbous 11 when we can see one half of the moon's disk to half to crescent to new (this is one-quarter of the entire moon's surface) Waxing Moon - when the moon seems to be getting bigger, going from new to crescent to half to gibbous to full Tides the moon pulling the earth Tides happen because both the Moon and the Sun pull the Earth's seawater towards them, by the force of their gravity. The Moon is so close to the Earth that it pulls more strongly on the side of the Earth facing it than it does on the far side of the Earth. As the Earth rotates on its axis, each part of its surface faces the Moon about once in every 24 hours. The seas at that point are most strongly attracted by the Moon. They rise up and cause a bulge of water we call high tide. Another matching bulge of water, or high tide, rises up on the other side of the Earth. The water to make the high tides comes from the areas between the two bulges. These areas experience low tides. There are two high tides and two low tides on opposite sides of the Earth every day. The Sun is so far away that the difference in its pull on opposite sides of the Earth is very small. However, twice a month, at full moon and new moon, the 12 Sun and the Moon pull towards Earth in line and produce tides that are higher than normal. These are called spring tides. When the Moon is at first and last quarter, it pulls at right angles to the Sun and produces small neap tides. At these times, the effect of the Moon's gravity on the oceans is partly offset by the Sun's gravity. DO THE TIDES COME AT THE SAME TIME EVERY DAY? The following table shows the times of high tide at Sydney, for one week in June 1997. Tuesday 3 Wednesday 4 Thursday 5 Friday 6 Saturday 7 Sunday 8 Monday 9 6.32 a.m. 7.26 a.m. 8.15 a.m. 9.02 a.m. 9.48 a.m. 10.31 a.m. 11.15a.m. 6.59 p.m. 7.45 p.m. 8.28 p.m. 9.10 p.m. 9.50 p.m. 10.30 p.m. 11.15a.m. CALCULATE 1. The difference between one high tide and the next, on the same day. ___________________________________________________________________________ 2. The difference between one high tide and the next on different days. ___________________________________________________________________________ 3. Starting with Tuesday 3 June, complete the following tables then answer the following questions. 6.32 a.m. minus 6.59 p.m. 7.26 a.m. minus 7.45 p.m. = = 12 hours 27 minutes 6.59 p.m. minus 7.26 a.m. = A 12 hours 27 minutes TABLE 7.45 p.m. minus 8.15 a.m. = TABLE B a. Do the tides change in a regular way? ___________________________________________________________________________ b. What is the greatest length of time between high tides? ___________________________________________________________________________ c. What is the smallest length of time? ___________________________________________________________________________ 13 d. What is the average length of time? (Add up results in both tables and divide by 14.) The tides are separated by more than 1 2 hours because the tidal bulges follow the Moon as it travels round the Earth every month. ___________________________________________________________________________ The seasons The Earth can be divided into two half-spheres, or hemispheres, separated by the Equator. It takes the Earth 365 1/4 days to complete one orbit of the Sun. As the Earth travels round the Sun, one hemisphere is always facing more towards the Sun than the other. This is because the axis of the Earth is tilted at an angle of 231/2 degrees to the Sun. We have our summer when the tilt of the Earth puts the Southern Hemisphere slightly nearer to the sun. In this position there is always more of the Southern Hemisphere than the Northern Hemisphere in sunlight. Six months later we are on the other side of our orbit. The tilt of the axis is still the same, but we are on the other side of the sun. The Southern Hemisphere is now tilted away from the sun. It is winter. The seasons in the Southern Hemisphere are opposite to those in the Northern Hemisphere. If the Southern Hemisphere is tilted towards the sun (summer), then the Northern Hemisphere is tilted away from the sun (winter). Activity 1. Look at the diagram below and fill in the missing words from the list provided: angle directly higher lower 23.5° northern revolves rotates six southern summer winter 14 The Earth ______________ around the Sun and, as it does so, it _____________ on its axis. The Earth’s axis is not vertical, but tilted _________ from vertical. This means that, in position A, the ____________ hemisphere is a little closer to the Sun than the _______________ hemisphere. Also, at position A, the Sun’s rays hit the southern hemisphere more ______________, while in the northern hemisphere the rays strike at more of an _____________. This means that we see the Sun ______________ in the sky from the southern hemisphere and ______________ in the sky from the northern hemisphere. At this time, the southern hemisphere is having ___________ and the northern hemisphere is having winter. ___________ months later, exactly the reverse happens, and the southern hemisphere experiences _____________. 2. Finish these sentences. a Our day is 24 hours long because that is the time it takes the Earth to: _____________________________________________________________________ _____________________________________________________________________ b A year has 365 days because that is the number of whole days it takes the Earth to: _____________________________________________________________________ _____________________________________________________________________ 3. There was a Full Moon on 15 October. The last quarter was on 22 October. New Moon was on 30 October. On 2 November the first quarter was showing. What will the Moon look like on 13 November? (Circle the correct alternative.) A B C 4. This illustration shows the Sun at midday on 21 June. Copy the illustration into your workbook and draw circles on it to show the Sun’s position at midday on 21 December and 21 March. Label the December Sun ‘D’ and the March Sun ‘M’. 15 5. Study the diagram below. Look at Ireland and Australia. a b c d Which Which Which Which country country country country is in daylight? _______________ is in darkness? _______________ is having winter? _______________ will have the longest period of daylight? _______________ 16 6. label the following: A New Moon B Full Moon C first quarter D last quarter Experiment explaining seasons Aim To use a model to explain how the tilting of the Earth's axis causes the seasons. Materials •a polystyrene ball (about 7 cm diameter) •a cooking skewer or knitting needle •a projector (OHP or slide projector) •two pins Method 1Place the polystyrene ball on the skewer. 2Hold the ball in the light from the projector, with its axis upright. 3Stick another pin in the ball to represent a person in the Northern Hemisphere. Place it so that you and the other person are both on the light-dark line. See the figure to the right. 4Rotate the ball to the sunset position. • Was the day the same length for both people? ___________________________________________________________________________ Return the ball to the sunrise position. 5Now tilt the top of the ball away from the projector, as shown in Fig to the right. Where does the sun rise first — at your place, or in the Northern Hemisphere? ___________________________________________________________________________ ______________ 6 Keep the ball tilted, and rotate it to the sunset position. •Where does the sun set first — at your place, or in the Northern Hemisphere? 17 ___________________________________________________________________________ •Who had the longer day? ___________________________________________________________________________ •With the axis tilted this way, is it summer or winter in Australia? ___________________________________________________________________________ •Is there any place on the Earth where the sun doesn't set? Is there any place where it is dark for 24 hours? ___________________________________________________________________________ 7 Repeat Steps 4 and 5, but this time tilt the top of the ball towards the projector. •In this position is it summer or winter in Australia? ___________________________________________________________________________ 8. Complete the following The Earth completes one rotation every ________________ hours giving us ________________ and ________________. Because the Earth is rotating the ________________ appears to move across the sky during the day. The path of the Earth around the ________________ is called an ________________ .The Earth takes ________________ days to complete one of these during which the Earth experiences the four different ________________ . The Sun is called a ________________ object since it gives out its own ________________.The Moon takes 28 days to go around the ________________ and during this time its appearance changes giving us the different ________________ occur when the ________________, Earth and Moon are all in one direct line and they occur when either the Earth or the Moon casts a ________________. The nine different ________________ and the ________________ is known as the Solar System. Mercury and ________________ are closer to the Sun than the Earth. This means that they take ________________ than one year to go around the ________________ once. All the other planets take ________________ than one year, except the ________________ which takes exactly one year. 18 The ________________ is made up of billions of galaxies with each one being made up of millions of ________________ one of which is the ________________ , The stars appear to move across the ________________ during the night because the earth is rotating. 9. Match the keywords from this unit to their definitions... Definition An object that does not give out light Made up of the Sun and the 9 different planets A planet that completes owe rotation every 24 hours The path taken by a planet around the sun A luminous object that is a continuous source of light This occurs when the Sun, Earth and Moon are all in one direct line These occur because the Earth moves around the Sun Made up of a billion galaxies Made up of a million stars Aw object that takes 28 days to orbit the Earth The Earth is one. Mars is owe, Pluto is one and soon Giant luminous object at the centre of the Solar System C ode A B C D E F G H I J Word EARTH ORBIT SEASONS SUN NON-LUMINOUS MOON ECLIPSE SOLAR SYSTEM1 PLANETS STAR Code 19 K L GALAXY UNIVERSE What is an eclipse? If you place your hand between a light source and your book, you will see a shadow on your book. This happens because your hand blocks the light. The same thing happens in space. If something passes between the Sun and another body, a shadow called an eclipse will be cast because the light from the Sun is blocked. What happens during an eclipse? As seen from the Earth, the Moon and the Sun appear to have nearly the same diameter. They look the same size, although the Sun is actually much bigger than the Moon. In space, the Sun, Moon and Earth change relative positions constantly. When the Moon passes between the Sun and the Earth, a solar eclipse occurs. The Moon's shadow falls on the Earth, but because the Moon is smaller than the Earth, only a small area of the Earth is covered by the shadow. This can only happen when the Sun, Moon and Earth are in a straight line, or aligned, at the time of the new moon. At least two and not more than five solar eclipses occur each year. A lunar eclipse occurs when the Moon moves into the Earth's shadow. All or part of the Moon appears dark. This can only happen when the Sun, Earth and Moon are in a straight line, at full moon. Eclipses can be either partial or total, depending on the position of the Sun, Moon and Earth. Label the Solar Eclipse Earth - the planet on which we live. Moon - the natural satellite of the Earth. Penumbra - the area in which the shadow of an object (the moon on the Earth) is partial, and the area in which a partial solar eclipse is experienced. Sun - the star in our Solar System. 20 Umbra - the area in which the shadow of an object (the moon on the Earth) is total, and the area in which a total solar eclipse is experienced. Label the Lunar Eclipse Earth - the planet on which we live. Moon - the natural satellite of the Earth. Penumbra - the area in which the shadow of an object (in this case, the Earth on the moon) is partial. Sun - the star in our Solar System. Umbra - the area in which the shadow of an object (in this case, the Earth on the moon) is total. When the entire moon is in the Earth's umbra, we experience a total lunar eclipse. When part of the moon is in the Earth's umbra, we experience a partial lunar eclipse. Find each of the following words. GALILEO ECLIPSE UMBRA ELLIPSE M G R E S M S T C L P I G E K B B E I E Y O E T I G S G A S H B O O S B E U E X L O H E O N E P C C I E S B N S G L P M G E H N SUN GIBBOUS MOON BLACK HOLES I E P S L M E L E G E E I R A E R N N R R O O L O D N R B E U C T T I S I B H O L C U N B C U S N R O E E B S S N E M A O P M A E I N E I O E E K L B S U S B N C C M E H E U S I C R O S E R L O L M E T S Y S T R A L O S A O WAXING PENUMBRA NEBULAE EARTH I C B A E L L L H R I L E E E L L M R E C G W A X I N G B D C P E N M I L C H T R A E S S I T U H G G T I I T C E R S E E T O C E A E I P R R A C S E L M S M N I L O C S G L E U B B T B G A R M I E H E U A N E A R M R N M I SOLAR SYSTEM HELIOCENTRIC GEOCENTRIC SPRING TIDES R L L U B S M I E B E N A I X T L E U E D B R P O S L O S R E I O O N E S P I L L E O B O P L C E O I A O S K H P O M O E S S I B I U G I L R I P P S E U C T H Main Ideas 21 1The Earth spins on its axis once every 24 hours, causing day and night. 2The Earth takes one year to revolve around the sun. 3A gravitational force of attraction keeps the Earth in orbit around the sun, and the moon in orbit around the Earth. 4The seasons are caused by the revolution of the Earth and the tilt of its axis. 5One complete revolution of the moon takes about 28 days. One rotation of the moon occurs in the same time. This is why the moon always keeps the same face towards the Earth. 6We see the moon because it reflects light from the sun. 7Changes in the sunlit part of the moon as it revolves around the Earth are called phases. 1 2 3 4 5 6 7 8 9 10 11 11 14 15 . 22 ACROSS CLUES 2 Thin, curved moon shape 4 Spring, summer, autumn and winter 7 Imaginary line through centre of Earth 9 Half a sphere 10Spins on an axis 11Oval shape 13Path of Earth around sun 14Moon shape before full moon 15Predicting the future using the stars DOWN GLUES 1 Changing shapes of the moon 3 Moves in an orbit 5Study of objects in space 6Used for looking at stars 8 Round like a ball 12 A ball can be used as a _________of the Earth 23 24 25 26 27