Earth, Sun and Moon · Grade 1
Earth spins on its axis once a day, giving day and night, and orbits the Sun once a year. Its axis is tilted, which gives us seasons – opposite in the two hemispheres. The Moon orbits Earth about once a month; as it does, we see different amounts of its sunlit half, giving the phases. Sometimes the three line up to make eclipses.
Key facts
- Day and night: Earth spins once every 24 hours. The Sun appears to move east → west.
- Seasons are caused by the tilt of Earth’s axis, not by our distance from the Sun.
- Solar eclipse: the Moon blocks the Sun (at new moon). Lunar eclipse: Earth’s shadow covers the Moon (at full moon).
- Earth turns 15° per hour, which sets time zones.
Worked examples
Example 1
It is summer in Cape Town in January. What season is it in London, and why?
Answer: winter – the hemispheres tilt opposite ways
Example 2
Tonight there is a first-quarter moon. What phase will it be in about a week, and in about two weeks?
Answer: full moon in a week; last quarter in two weeks