Earth Moon and the Sun
Day and night, the changing seasons, the shifting shape of the Moon and the drama of eclipses all come from the motions of the Earth, Moon and Sun. This Class 7 Curiosity chapter explains rotation and revolution, the phases of the Moon, and how eclipses happen.
Learning objectives
- Explain day and night from rotation.
- Explain seasons from revolution and tilt.
- Describe the phases of the Moon.
- Explain solar and lunar eclipses.
Key concepts
Rotation and day and night
The Earth spins on its axis, an imaginary line through its poles; this spinning is called rotation and takes about 24 hours. As the Earth rotates, the side facing the Sun has day and the side facing away has night. So day and night are caused by the Earth's rotation, not by the Sun moving.
Revolution and seasons
The Earth also moves around the Sun in a path called its orbit; one full round, called a revolution, takes about a year. Because the Earth's axis is tilted, different parts receive the Sun's rays more directly at different times of the year, which causes the seasons such as summer and winter.
Phases of the Moon
The Moon does not give its own light; it shines by reflecting sunlight. As the Moon revolves around the Earth, we see different amounts of its lit half, producing the phases — from new moon (not visible) to full moon and back. This cycle repeats about every month.
Eclipses
An eclipse happens when one body's shadow falls on another. In a solar eclipse, the Moon comes between the Sun and the Earth, blocking the Sun's light for a while. In a lunar eclipse, the Earth comes between the Sun and the Moon, so the Earth's shadow falls on the Moon. We should never look directly at the Sun during a solar eclipse.
Key definitions
- Rotation
- The spinning of the Earth on its axis, causing day and night.
- Revolution
- The movement of the Earth around the Sun, taking about a year.
- Phase of the Moon
- The shape of the lit part of the Moon that we see.
- Eclipse
- An event when the shadow of one body falls on another.
Solved examples
Q1. What causes day and night?
Solution: The rotation of the Earth on its axis.
Q2. Why does the Moon shine?
Solution: It reflects sunlight; it has no light of its own.
Q3. In a solar eclipse, which body is in the middle?
Solution: The Moon, between the Sun and the Earth.
Common mistakes to avoid
- Thinking the Sun moves around the Earth to cause day and night.
- Believing the Moon produces its own light.
- Confusing rotation (spin) with revolution (orbit).
- Swapping the positions of bodies in solar and lunar eclipses.
Earth Moon and the Sun — MCQ Quiz
10 questions with instant feedback. Use number keys 1–4 to answer.
Day and night are caused by the Earth's:
Practice questions
Short answer
What causes day and night?
The rotation of the Earth on its axis.
Why does the Moon have phases?
Because we see different amounts of its sunlit half as it orbits the Earth.
What is a solar eclipse?
When the Moon comes between the Sun and Earth and blocks the Sun's light.
Long answer
Explain how the rotation and revolution of the Earth cause day, night and the seasons.
The Earth has two main motions. It spins on its axis — an imaginary line through its poles — and this rotation takes about 24 hours; as it spins, the half facing the Sun experiences day while the half facing away experiences night, so rotation causes day and night. The Earth also moves around the Sun in an orbit, completing one revolution in about a year. Because the Earth's axis is tilted, different parts of the Earth receive the Sun's rays more directly at different points in this orbit. When a region is tilted towards the Sun it gets more direct sunlight and has summer; when tilted away it has winter. So the seasons arise from the Earth's revolution combined with the tilt of its axis.
Describe how solar and lunar eclipses occur, and why eye safety matters.
An eclipse occurs when the shadow of one heavenly body falls on another, and this depends on the Sun, Earth and Moon lining up. In a solar eclipse, the Moon comes between the Sun and the Earth, so the Moon's shadow falls on part of the Earth and the Sun is blocked from view for a short time during the day. In a lunar eclipse, the Earth comes between the Sun and the Moon, so the Earth's shadow falls on the Moon and the Moon darkens. During a solar eclipse one must never look directly at the Sun, even when it is mostly covered, because its light can permanently damage the eyes; safe viewing methods or special filters should always be used.
HOTS (Higher Order Thinking)
If the Earth did not rotate, what would happen to day and night?
One side would have continuous day and the other continuous night, instead of the regular cycle we experience.
Why do we always see nearly the same face of the Moon?
Because the Moon takes the same time to rotate once as it does to revolve once around the Earth, so the same side faces us.
Quick revision
Revision notes
- Rotation (≈24 h) on the axis → day and night.
- Revolution (≈1 year) + axial tilt → seasons.
- Moon reflects sunlight; its phases repeat about monthly.
- Solar eclipse: Moon between Sun and Earth; lunar eclipse: Earth between Sun and Moon.
Key takeaways
- Day/night come from rotation; seasons from revolution + tilt.
- The Moon shines by reflected sunlight.
- Eclipses happen when bodies line up and cast shadows.
Frequently asked questions
Does the Sun move to make day and night?
No — the Earth's rotation causes day and night.
Why are there seasons?
Because the Earth revolves around the Sun with a tilted axis.
What is the difference between a solar and lunar eclipse?
Solar: the Moon blocks the Sun; lunar: the Earth's shadow falls on the Moon.