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The Earth and Space - Rotation and Revolution of the Earth

Grade 4CBSE

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

🔑Concepts

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The Earth has an imaginary line called the axis that runs through its center from the North Pole to the South Pole, tilted at an angle of 23.5∘23.5^\circ.

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Rotation is the spinning movement of the Earth on its axis. One full rotation takes approximately 2424 hours (one day).

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The rotation of the Earth causes day and night. The side facing the Sun experiences day, while the side facing away experiences night.

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Revolution is the movement of the Earth around the Sun in a fixed, elliptical path called an orbit.

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One complete revolution takes about 36514365 \frac{1}{4} days, which constitutes one solar year.

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The tilted axis (23.5∘23.5^\circ) combined with the Earth's revolution causes the change in seasons (Summer, Winter, Autumn, and Spring).

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A Leap Year occurs every 44 years and has 366366 days because the 44 quarter-days (14+14+14+14\frac{1}{4} + \frac{1}{4} + \frac{1}{4} + \frac{1}{4}) from the revolution period are added together to make one full day.

📐Formulae

1 Rotation≈24 hours1 \text{ Rotation} \approx 24 \text{ hours}

1 Revolution≈36514 days1 \text{ Revolution} \approx 365 \frac{1}{4} \text{ days}

4×14 day=1 day (Added to February every 4th year)4 \times \frac{1}{4} \text{ day} = 1 \text{ day (Added to February every 4th year)}

Tilt of Earth’s Axis=23.5∘\text{Tilt of Earth's Axis} = 23.5^\circ

💡Examples

Problem 1:

If the Earth takes 36514365 \frac{1}{4} days to complete one revolution, how many days will there be in total after 44 years?

Solution:

The total number of days is 14611461 days.

Explanation:

To find the total, we calculate: (365×4)+(14×4)=1460+1=1461(365 \times 4) + (\frac{1}{4} \times 4) = 1460 + 1 = 1461 days. This extra 11 day is why every fourth year is a leap year with 366366 days instead of 365365.

Problem 2:

Why is it day in India when it is night in the United States of America?

Solution:

This is due to the Earth's rotation on its axis.

Explanation:

Because the Earth is a sphere and rotates on its axis, only half of it faces the Sun at any given time. India and the USA are on roughly opposite sides of the globe. When India faces the Sun (DayDay), the USA is tilted away from the Sun (NightNight).

Problem 3:

What would happen to the seasons if the Earth's axis was not tilted (at 0∘0^\circ instead of 23.5∘23.5^\circ)?

Solution:

There would be no change in seasons throughout the year.

Explanation:

Seasons are caused by the tilt of the Earth. If the tilt was 0∘0^\circ, the Sun's rays would hit the same latitudes with the same intensity all year round as the Earth revolves, resulting in constant weather patterns.