AC9S7U03 • Homework
Earth, Sun & Moon Cycles
Use relative positions, illumination, gravity and model limitations to explain predictable phenomena. Diagrams may be used where they strengthen your explanation.
Part A — Short response
- Explain why Earth's axial tilt causes seasons. (2)
- Describe how the angle of incoming sunlight affects energy intensity at Earth's surface. (2)
- State the main astronomical causes of high and low tides. (2)
- Explain why we see different lunar phases during a month. (2)
- State one difference between a solar eclipse and a lunar eclipse. (2)
Part B — Extended response
- Use a physical or virtual model to explain how Earth's tilt and orbit create opposite seasons in the two hemispheres. Include Sun angle, day length and one limitation of the model. (5)
- Explain how the relative positions of the Sun, Earth and Moon produce spring and neap tides. Include which lunar phases are associated with each and why tidal range changes. (5)
- Describe the lunar phase cycle and explain the geometry of solar and lunar eclipses. Explain why eclipses do not occur every new and full moon. (5)
- Using a reliably sourced example supplied by your teacher or source material, explain how a particular First Nations Australian community connects lunar observations with tides or other coastal conditions. Identify the People/Country or Place and avoid generalising the example to all communities. (5)
- Explain how a place-specific First Nations Australian seasonal calendar can use recurring plant, animal, weather and sky indicators to predict seasonal change. Compare this approach with a fixed four-season calendar. (5)
Part C — Enrichment
11. Earth–Sun–Moon cycle analysis. Analyse how cyclic changes in the relative positions of Earth, the Sun and the Moon influence seasons, tides, lunar phases and eclipses. Evaluate how physical or digital models help explain these phenomena, identify at least two model limitations, and explain how accurately sourced First Nations Australian seasonal, lunar or eclipse knowledge can be compared respectfully with contemporary astronomical models.
Answers and marking guide
1
Earth's axis is tilted about 23.5°. As Earth orbits, each hemisphere alternately tilts toward or away from the Sun, changing Sun angle and day length.
2
More direct sunlight concentrates incoming energy over a smaller surface area; lower-angle sunlight spreads similar incoming energy over a larger area.
3
Tides are driven mainly by the Moon's differential gravitational effect on Earth, with the Sun also contributing. Earth's rotation carries locations through the tidal pattern.
4
The Sun illuminates about half the Moon. As the Moon orbits Earth, we see changing fractions of that illuminated half.
5
Solar eclipse: Moon between Earth and Sun, Moon's shadow falls on Earth. Lunar eclipse: Earth between Sun and Moon, Moon enters Earth's shadow.
6
Tilt changes Sun angle and daylight duration. The hemisphere tilted toward the Sun receives more direct sunlight and longer days; the other receives less direct sunlight and shorter days. A classroom model normally distorts real sizes/distances.
7
Spring tides occur near new/full moon when Sun-Earth-Moon are approximately aligned and solar/lunar tidal effects reinforce. Neap tides occur near first/third quarter when the Sun and Moon appear roughly 90° apart and the effects partly oppose.
8
Phases progress new → waxing → full → waning → new over about 29.5 days. Solar eclipses require new-moon alignment; lunar eclipses require full-moon alignment. The Moon's orbital plane is tilted, so most new/full moons miss exact shadow alignment.
9
Answers depend on the supplied source. Full credit requires accurate attribution to a particular People/Country or Place, a supported connection between lunar observations and tides/coastal conditions, and no claim that the example represents all First Nations Australians.
10
A place-specific seasonal calendar may use recurring flowering, animal behaviour, weather, water and sky indicators. Unlike a fixed four-season calendar, boundaries can be signalled by local ecological events rather than fixed dates. Specific knowledge must be accurately attributed.
11
Full-credit answers connect tilt/orbit to seasons, gravity/alignment to tidal variation, illumination geometry to phases, and shadow alignment plus orbital inclination to eclipses. They evaluate scale/simplification limits of models and compare First Nations knowledge only through reliably sourced, place-aware examples.