The Earth, Sun and Moon: Seasons, Eclipses and Tides — Answers
Answer sheet with model answers and success criteria for the Year 7 the solar system & space worksheet.
Success TutoringWorksheetsAnswer sheetYear 7 · Science · The Solar System & SpaceThe Earth, Sun and Moon: Seasons, Eclipses and Tides — Answers
Part A: Why we have seasons
Earth rotates on its axis once a day and orbits (revolves around) the Sun about once every 365¼ days. Its axis is tilted at about 23.5°, and the axis keeps pointing in the same direction in space all the way around the orbit.
Because of this, for part of the year the southern hemisphere leans towards the Sun, and half an orbit later the northern hemisphere does. The hemisphere tilted towards the Sun has summer: the Sun climbs higher in the sky, its light hits the ground more directly and days are longer. The hemisphere tilted away has winter at the same time.
Between these two positions are the equinoxes, when neither hemisphere leans towards the Sun and day and night are about equal everywhere. The longest and shortest days of the year are the solstices.
A common mistake is to think the seasons are caused by Earth's changing distance from the Sun. Earth's orbit is almost a circle, and Earth is actually closest to the Sun during the northern hemisphere's winter.
- AThe tilt of Earth's axis as Earth orbits the Sun
- BEarth moving closer to and further from the Sun
- CThe Moon blocking some of the Sun's light
- DEarth spinning faster at some times of the year
Answer: The tilt of Earth's axis as Earth orbits the Sun
Earth's axis is tilted, and it stays pointing in the same direction in space as Earth orbits the Sun. For part of the orbit one hemisphere leans towards the Sun, and for the opposite part of the orbit the other hemisphere does.
- AWinter
- BSummer
- CSpring
- DAutumn
Answer: Winter
When one hemisphere is tilted towards the Sun (summer), the other is tilted away from it (winter). The seasons in the two hemispheres are always opposite.
Answer: False
Both hemispheres cannot have summer at the same time. In fact, Earth is closest to the Sun during the northern hemisphere's winter. Earth's orbit is nearly circular, so the change in distance is small and is not what causes the seasons.
Answer: 1. Sunlight strikes it more directly (the Sun is higher in the sky), so the same energy is concentrated on a smaller area of ground. 2. Days are longer and nights shorter, so there are more hours of heating each day.
Answer: 23.5
The tilt is about 23.5° from upright (measured from a line at right angles to the plane of Earth's orbit).
Answer: Day and night are about the same length (about 12 hours each) everywhere on Earth.
Answer: At the equator the midday Sun is high in the sky all year, so sunlight is fairly direct in every season, and the day length stays close to 12 hours all year. The tilt changes conditions there much less than it does closer to the poles.
Answer: In summer the pole is tilted towards the Sun, so as Earth rotates that region never turns away into darkness. In winter the pole is tilted away, so it stays in Earth's shadow even as Earth rotates.
Part B: Eclipses
An eclipse happens when the Sun, Earth and Moon line up and one body moves into the shadow of another.
- Solar eclipse
- Lunar eclipse
- Total solar eclipse
- Partial eclipse
- The Moon completely covers the Sun's bright disc for people in a narrow path on Earth
- Only part of the Sun (or Moon) is covered or darkened
- The Moon passes between the Sun and Earth, and the Moon's shadow falls on Earth
- Earth passes between the Sun and the Moon, and Earth's shadow falls on the Moon
Answer: Solar eclipse → The Moon passes between the Sun and Earth, and the Moon's shadow falls on Earth; Lunar eclipse → Earth passes between the Sun and the Moon, and Earth's shadow falls on the Moon; Total solar eclipse → The Moon completely covers the Sun's bright disc for people in a narrow path on Earth; Partial eclipse → Only part of the Sun (or Moon) is covered or darkened
- ANew moon
- BFull moon
- CFirst quarter
- DLast quarter
Answer: New moon
The Moon must be between the Sun and Earth, which is the new moon position (its sunlit side faces away from us).
- AFull moon
- BNew moon
- CFirst quarter
- DWaning crescent
Answer: Full moon
Earth must be between the Sun and the Moon, which is the full moon position.
Answer: The Moon's orbit is tilted (by about 5°) compared with Earth's orbit around the Sun. At most new moons the Moon passes slightly above or below the line from the Sun to Earth, so its shadow misses Earth.
Answer: Some sunlight is bent (refracted) through Earth's atmosphere into the shadow. The atmosphere scatters away most of the blue light, so mainly red light reaches the Moon.
Answer: True
A lunar eclipse is just a darkened Moon, so it is safe to watch. Looking at the Sun can permanently damage your eyes; solar eclipses should only be viewed with proper solar eclipse glasses or by projecting an image.
Answer: The Sun is also about 400 times further away from Earth than the Moon is, so the two appear almost the same size in our sky.
Part C: Tides
The tide is the regular rise and fall of the sea level. It is caused mainly by the gravitational pull of the Moon on Earth's oceans, with a smaller effect from the Sun.
The Moon pulls the ocean into two bulges, one facing the Moon and one on the far side of Earth. As Earth rotates, coastal places move through these bulges, which gives high tides, and through the areas between them, which gives low tides.
- AThe gravitational pull of the Moon
- BWind blowing across the ocean
- CEarth's magnetic field
- DThe heat of the Sun
Answer: The gravitational pull of the Moon
The Moon's gravity pulls on Earth's oceans. The Sun's gravity also causes tides, but its effect is less than half as strong as the Moon's because the Sun is so much further away.
Answer: The ocean forms two bulges: one on the side of Earth facing the Moon and one on the opposite side. As Earth rotates, a place on the coast passes through both bulges (high tides) and the two low areas between them (low tides).
Answer: At about 6:25 pm (roughly 12 hours and 25 minutes later).
- Spring tide
- Neap tide
- Smaller difference between high and low tide, when the Sun and Moon pull at right angles
- Very high high tides and very low low tides, when the Sun, Earth and Moon are in a line
Answer: Spring tide → Very high high tides and very low low tides, when the Sun, Earth and Moon are in a line; Neap tide → Smaller difference between high and low tide, when the Sun and Moon pull at right angles
- ANew moon and full moon
- BFirst quarter and last quarter
- COnly at full moon
- DOnly in the season of spring
Answer: New moon and full moon
At new and full moon the Sun, Earth and Moon line up, so the Sun's and Moon's tidal effects add together. The name has nothing to do with the season: it comes from the water springing up higher.
Answer: True
At the quarter phases the Sun and Moon are at right angles as seen from Earth, so their tidal effects partly cancel, giving a smaller tidal range.
Part D: Explain it
Model answer: Solar eclipse: Sun — Moon — Earth in a straight line, with the Moon's shadow reaching part of Earth. The Moon blocks sunlight from reaching that part of Earth; it happens at new moon. Lunar eclipse: Sun — Earth — Moon in a straight line, with Earth's shadow falling on the Moon. Earth blocks sunlight from reaching the Moon; it happens at full moon.
Success criteria:
- Correct order of Sun, Moon and Earth for a solar eclipse
- Correct order of Sun, Earth and Moon for a lunar eclipse
- Shadows shown and labelled
- Correct Moon phase given for each
Model answer: If distance caused the seasons, both hemispheres would have summer at the same time, but they always have opposite seasons. Earth's orbit is nearly circular, and Earth is actually closest to the Sun during the northern hemisphere's winter. The real cause is the tilt of Earth's axis. The hemisphere tilted towards the Sun receives more direct sunlight, so the energy is concentrated on a smaller area, and it has longer days, so it is summer there. The hemisphere tilted away receives less direct sunlight and has shorter days, so it is winter there.
Success criteria:
- Points out that the hemispheres have opposite seasons
- States that distance is not the cause (orbit nearly circular)
- Explains tilt and more direct sunlight
- Mentions longer days
Marking tips
- Give credit for correct method even when the final answer slips — the working shows where the thinking went right.
- For open-ended tasks, use the success criteria as a checklist rather than looking for one "right" answer.
- Celebrate what went well first, then pick one thing to work on next.
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