Earth, Sun and Moon: Day, Night and Seasons: Grade 5 Study Guide
The motions of Earth and the Moon explain many of the patterns we see in the sky.
Earth rotates (spins) once about every 24 hours on its axis, so the side facing the Sun has day while the opposite side has night. The Sun appears to rise in the east and set in the west because of this spin. Shadows are longest in the early morning and late afternoon, and shortest near midday.
Earth also revolves (orbits) around the Sun once every year (about 365 days). Earth's axis is tilted, which gives us seasons. The Moon orbits Earth about every month.
Seasons
Because the axis is tilted about 23.5°, different parts of Earth lean toward the Sun at different times of the year. When the Northern Hemisphere leans toward the Sun, it has summer: longer days and more direct sunlight. At the same time, the Southern Hemisphere has winter. Seasons are not caused by distance from the Sun.
| Time of year | Northern Hemisphere | Southern Hemisphere |
|---|---|---|
| June to August | summer | winter |
| September to November | autumn (fall) | spring |
| December to February | winter | summer |
| March to May | spring | autumn |
The Moon's phases
The Moon makes no light of its own; we see sunlight reflected from it. Half of the Moon is always lit by the Sun, but as it orbits Earth we see different amounts of the lit half. The cycle takes about 29.5 days.
The lit side faces away from us.
A growing crescent, then a first quarter.
The whole lit side faces us.
It shrinks to a last quarter and crescent.
Stars and gravity
Stars are far-away suns. The Sun looks bigger and brighter than other stars only because it is much closer. Gravity is the force that pulls objects toward the center of Earth, which is why things fall down everywhere on the planet, including in Australia. Gravity also keeps the Moon in orbit around Earth and Earth in orbit around the Sun.
Worked example and common misconceptions
Example: A shadow stick measured every hour shows the shadow shrinking toward midday and growing again. Common misconceptions: believing seasons depend on distance from the Sun, that the Moon phases are caused by Earth's shadow (that is an eclipse) and that the Sun moves around Earth. Model the motions with a lamp and a ball in a dark room.
Check your understanding: model answers
1. About 365 days. 2. The tilt of Earth's axis as it orbits the Sun. 3. We see different parts of its sunlit half as it orbits Earth.
✨ Key Takeaways
- Earth's rotation causes day and night.
- Earth's tilt causes seasons.
- Moon phases come from our changing view of its lit half.
- Gravity pulls objects toward Earth's center.
💬 Questions for Discussion & Reflection
- How long does Earth take to orbit the Sun?
- What causes the seasons?
- Why do we see different Moon phases?
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