What are the relative movements of the Earth, sun and moon? Content focus: Inquiry skills focus:
The lessons
Comparing the rotation and revolution of the Earth, the sun and the moon
• Pages 75 and 76 should be used together. A globe of the Earth would be useful to show rotation, along with a torch to represent the sun. The animations on the suggested websites will give students a 3-D view of the rotation and revolution of the sun, Earth and moon.
Planning and conducting Processing and analysing data and information Evaluating Communicating
• Students should choose from the suggested equipment/materials the teacher provides to make their models for page 77 or add their own suggestions.
r o e t s Bo r e p ok u S Answers
Background information
Page 76
1. Possible answers: Telescopes hadn’t been invented which helped astronomical discoveries/people saw the sun, moon, stars and so on 'move across the sky' from Earth so presumed they revolved around Earth and not the sun. 2. Galileo used a telescope to view sunspots that appeared to move across the face of the sun. Their motion proved the sun rotates. 3. (a) It means that different parts of the sun rotate at different speeds. (b) Because the sun is composed of gases and the Earth and the moon are composed (largely) of rock. 4.
• A solar year is the time taken for the Earth to make one complete revolution around the sun. It is measured from one equinox to the next (time of equal day and night). • A dwarf planet is a space body that is large enough to be rounded by its own gravity but not gravitationally dominant in its orbital area and is not a moon. A plutoid is a dwarf planet further from the sun than Neptune.
ew i ev Pr
Teac he r
• Ancient philosophers/astronomers assumed the sun, moon, stars and planets visible to the naked eye all revolved around the Earth each day, believing the Earth to be the centre of the universe. The invention and use of the telescope to view further into space and see more accurately saw this geocentric (Earth as centre) theory gradually change. Gallileo was the first person to use a refracting telescope to observe and identify astronomic discoveries.
Preparation
. te
Moon
24 hours (1 day)
27.3 days
Time to complete one rotation
≈ 25 days ≈ 31 days at poles
What does it orbit?
Milky Way Galaxy
Sun
Earth (and sun)
Orbital speed
780 000 km/h
107 000 km/h
3600 km/h
Time to complete one orbit
230 million years
365 days (and just under 6 hours)
27.3 days
5. It means that moon makes one rotation and revolution in the same length of time. Science as a Human Endeavour question Nature and development of science Students should discover he used trigonometric methods (an important advancement) rather than geometric methods in his calculations. Useful website: <www.famousscientists.org/al-battani/>
o c . che e r o t r s super
• Reference books or the internet will need to be available for students to answer the final question on page 76.
Page 77
• Collect equipment needed for the modelling demonstration activities on page 77. Suggestions for sun, Earth and moon models: different sized polystyrene balls; balloons, newspapers and glue for papier mâché models; different sized balls, different sized round fruit. Axes: skewers, dowelling, rulers, straws. Torches for sun’s light. Swivel chairs for students to model rotation. Materials for making labels and charts. Digital camera or video equipment for photographs/filming of the demonstrations. Globe of Earth. Cellophane, cottonwool, crepe paper, cardboard and other suitable art materials to use in creating the surface of the sun, Earth and moon.
AUSTRALIAN CURRICULUM SCIENCE
Earth
m . u
• Useful websites: − <http://suntrek.org/sun-as-a-star/suns-vital-statistics/does-sunrotate.shtml> (animation and written information about the sun’s differential rotation) − <http://www.fearofphysics.com/SunMoon/sunmoon1.html> (animation of Earth and moon rotating while revolving around the sun) − <http://www.youtube.com/watch?v=lkWyM-M8o0c> (Earth rotating and orbiting sun while sun orbits galaxy) − <http://www.youtube.com/watch?v=OZIB_leg75Q> (animation and written information of synchronous rotation of moon)
w ww
Earth and space sciences
© R. I . C.Publ i cat i ons •f orr evi ew pur posesonl y• Sun
The aim of the activity is for students to show their understanding of what they have learnt on page 75 by using models, other props and themselves to demonstrate how each space body rotates and revolves. After the demonstration, the teacher and student audience can rate the performance (score out of 10) and suggest what they didn’t understand or could have been explained or demonstrated better.
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