The Earth’s Revolution – SS1 Geography Lesson Note (First Term)

Revolution is the movement of one body around another. The earth revolves around the sun in its orbit once in approximately 365¼ days, which is one year, while the moon revolves around the earth once a month. This movement produces the seasons, leap years and changes in the length of day and night.

Behavioural objectives

By the end of the lesson, students should be able to:

• define revolution;
• state the time the earth takes to revolve around the sun;
• explain what a leap year is;
• distinguish between a solar eclipse and a lunar eclipse;
• state the effects of the earth’s revolution.

What is revolution?

The word “revolution” refers to the movement of one body around another. The moon revolves around the earth, while the earth revolves around the sun.

The moon revolves around the earth once a month. The earth and moon travel together and make a complete trip around the sun once a year.

Revolution is the movement of the earth in its orbit around the sun once in approximately 365¼ days, that is, one year.

What is a leap year?

Every fourth year has 366 days, and this is called a leap year. All other years have 365 days.

How do eclipses occur?

Eclipses occur when the three bodies, the sun, the earth and the moon, are in a straight line.

What are the effects of the earth’s revolution?

1. It determines a year. The time a planet takes to complete one revolution around the sun determines one year on that planet. One year on earth is 365¼ days.
2. It determines the seasons. There are two main seasons in the tropical belt, the rainy and dry seasons. In the temperate belt, there are four distinct seasons: summer, autumn, winter and spring.
3. Changes in the altitude of the mid-day sun. These changes are seen in the equinoxes and solstices.
4. Varying length of day and night at different times of the year. The length of day and night varies with the position of the earth around the sun.
5. Changes in seasonal temperature. In the Arctic region, summers are usually warm and bright, while winters are cold and dark.
6. Dawn and twilight. Dawn is the brief period between sunrise and full daylight. Twilight is the brief period between sunset and complete darkness.

Evaluation

1. Define revolution.
2. How long does the earth take to complete one revolution around the sun?
3. What is a leap year, and how many days does it have?
4. Name the type of eclipse that occurs when the moon is between the earth and the sun.

Assignment

1. Explain the earth’s revolution.
2. State four effects of the earth’s revolution.