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SCIENCE ESSENTIALS 7 Australian Curriculum Edition



Comparing planets

Use the planetary data in the following table to answer the questions below. Planet

Time to orbit sun (Earth years) Mercury 0.2 Venus 0.6 Earth 1 Mars 1.9 Jupiter 11.9 Saturn 29.5 Uranus 84 Neptune 165         

Time to spin T ilt of axis on axis (degrees) (h = hours, d = days) 59 d 0 243 d 177 24 h 23½ 25 h 25 10 h 3 11 h 27 17 h 98 16 h 30

Which planet takes the longest time to orbit the sun? Which planet has the shortest year? How do you know? Write a generalisation linking the length of a planet’s year to its distance from the sun. Which planet has the shortest day? On which planet would a day be about the same length as a day on Earth? Draw a diagram showing how all the planets are tilted. Which planets have seasons similar to those on Earth? Explain your reasoning Would there be seasons on Mercury? Explain. The axis of one planet is so tilted that it spins on its side. Which one? What would the seasons be like on this planet?

Over to you 1 In which direction does the sun move across the sky? What makes it appear to move this way? 2 Explain in your own words what causes day and night. Use a diagram to help you explain. 3 a Use a diagram to explain the difference between the revolution and the rotation of the Earth. b How long does it take the Earth to complete one rotation?

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c How long does it take the Earth to complete one revolution? 4 Look at the diagram below showing four different places on Earth, marked with the letters A–D.



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a Which places are in the Southern Hemisphere? Which are in the Northern Hemisphere? b In which of these places is it daylight with the Earth in this position? c In which places is it night? d Of the places in daylight, which one will have sunset first? e Of the places where it is night, which will have sunrise first? f Which places are experiencing summer? g Which place will have the longest day? The shortest day? People once thought the sun moved around the Earth. a Why do you think it is possible for people to have this idea? b How do we know that this idea is wrong? Why is the sunshine stronger in summer than in winter? Places on Earth where the sun doesn’t set during summer are called the Land of the Midnight Sun. Where are these places? What would be different in our lives if: a the Earth rotated in 50 hours b the Earth took only half as long to complete its orbit around the sun c the Earth’s axis was not tilted? What causes the length of daylight to change during the year?

3/03/11 5:04 PM

Science Essentials 7 AC edition  
Science Essentials 7 AC edition  

Science Essentials 7 AC edition sample pages