Junior Cycle Science Quiz: The Earth–Sun–Moon System
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1. The Earth-Sun-Moon System
  • The Sun, Earth, and Moon interact in a way that creates seasons, lunar phases, and eclipses.
  • The Earth orbits the Sun, while the Moon orbits the Earth.

2. Seasons
  • The Earth is tilted at 23.5° on its axis.
  • As it orbits the Sun, different parts of the Earth receive varying amounts of sunlight, causing seasons.
How Seasons Work:
  • Summer: The hemisphere tilted toward the Sun experiences more direct sunlight and longer days.
  • Winter: The hemisphere tilted away from the Sun receives less sunlight and has shorter days.
  • Spring & Autumn: These are transition periods where day and night are nearly equal.

​Important Fact: The seasons are NOT caused by how close the Earth is to the Sun but by the tilt of Earth's axis.

3. Lunar Phases
  • The Moon does not produce its own light; it reflects sunlight.
  • As the Moon orbits the Earth, different portions of its sunlit side become visible, creating lunar phases.
The 8 Lunar Phases:
  1. New Moon – The Moon is between the Earth and the Sun; no part is visible.
  2. Waxing Crescent – A small lit crescent appears.
  3. First Quarter – Half of the Moon is lit.
  4. Waxing Gibbous – More than half is lit, growing toward a full moon.
  5. Full Moon – The entire face of the Moon is visible.
  6. Waning Gibbous – The lit portion starts decreasing.
  7. Last Quarter – Half of the Moon is visible again.
  8. Waning Crescent – A small lit crescent appears before returning to a New Moon.
Key Idea: The Moon takes about 29.5 days to complete one cycle of phases.

4. Eclipses
  • An eclipse happens when one celestial body moves into the shadow of another.
1. Solar Eclipse (Sun is blocked)
  • Occurs when the Moon moves between the Earth and the Sun, blocking sunlight.
  • This happens during a New Moon phase.
  • Types of solar eclipses:
    • Total – The Sun is completely blocked.
    • Partial – Only part of the Sun is covered.
    • Annular – The Moon appears smaller and leaves a ring of sunlight visible.
2. Lunar Eclipse (Moon is blocked)
  • Occurs when the Earth moves between the Sun and the Moon, casting a shadow on the Moon.
  • This happens during a Full Moon phase.
  • Types of lunar eclipses:
    • Total – The entire Moon moves into Earth's shadow.
    • Partial – Only part of the Moon is in shadow.

5. Summary
  • The tilt of Earth’s axis causes seasons.
  • The Moon’s orbit around Earth causes lunar phases.
  • Solar and lunar eclipses occur due to the alignment of the Sun, Earth, and Moon.
  • These events are predictable based on the movements of celestial bodies.

Phases of the Moon

Solar and Lunar Eclipses