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Earth and Space - The movement of the Earth relative to the Sun

Grade 4IGCSE

Review the key concepts, formulae, and examples before starting your quiz.

🔑Concepts

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The Earth rotates on an imaginary line called an axis. This axis runs from the North Pole to the South Pole. One full rotation takes approximately 2424 hours, which creates the cycle of day and night.

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The Earth orbits (revolves) around the Sun. This path is called an orbit. It takes the Earth 36514365 \frac{1}{4} days to complete one full revolution around the Sun.

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The Earth's axis is not straight; it is tilted at an angle of approximately 23.5∘23.5^{\circ}. This tilt, combined with the Earth's orbit, is responsible for the changing seasons.

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Because the Earth rotates from West to East, the Sun appears to rise in the East and set in the West. This is known as the Sun's apparent motion.

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Shadows change throughout the day due to the Earth's rotation. When the Sun is low in the sky (morning and evening), shadows are long. When the Sun is at its highest point (noon), shadows are at their shortest.

📐Formulae

1 Rotation=24 hours1 \text{ Rotation} = 24 \text{ hours}

1 Revolution≈365.25 days1 \text{ Revolution} \approx 365.25 \text{ days}

Earth’s Tilt≈23.5∘\text{Earth's Tilt} \approx 23.5^{\circ}

💡Examples

Problem 1:

If the Earth takes 36514365 \frac{1}{4} days to orbit the Sun once, how many days does it take to complete 44 full orbits?

Solution:

14611461 days

Explanation:

To find the total days, we multiply the time for one orbit by 44: 4×365.25=14614 \times 365.25 = 1461 This is why we have a 'Leap Year' with an extra day every 44 years.

Problem 2:

A student notices that a flagpole casts a shadow that is 1010 meters long at 8:008:00 AM. At 12:0012:00 PM, will the shadow be longer or shorter?

Solution:

Shorter

Explanation:

At 12:0012:00 PM (noon), the Sun is at its highest point in the sky relative to the observer. The higher the light source, the shorter the shadow cast by the object.

Problem 3:

If it is currently daytime in the United Kingdom, what is happening on the exact opposite side of the Earth (e.g., near New Zealand)?

Solution:

It is night-time.

Explanation:

Because the Earth is a sphere, the Sun's rays can only hit one half of the Earth at a time. The side facing the Sun experiences DayDay, while the side facing away experiences NightNight.