Basic 5 · Science · Earth Science
How Day and Night Are Formed
In this topic you will learn how the rotation of the earth on its axis causes day and night.
By the end of these notes you should be able to:
- Explain the rotation of the earth
- Describe how day and night are formed
- Explain why the sun appears to rise and set
What you already know
- The sun and the earth (Basic 4)
Copy everything that has a blue line on its left into your notebook. The other parts are for reading.
- Strand
- Cycles
- Sub-strand
- Earth Science
- Indicator
- B5.2.1.1.1 – Know how day and night are formed
Introduction
Every morning the sun appears in the east and every evening it disappears in the west. It looks as if the sun moves around the earth. In fact, the earth is spinning.
1. The Earth Rotates
Rotation: The spinning of the earth on its axis.
The earth is shaped like a ball. It spins on an imaginary line called the axis, which runs through the North Pole and the South Pole. The earth turns from west to east. One complete rotation takes about 24 hours, which is one day.
2. Day and Night
The sun gives out light, but it can only shine on one half of the earth at a time. The half facing the sun has daytime. The half facing away from the sun is in darkness and has night. As the earth rotates, places move from the lit half into the dark half and back again. That is why day and night follow each other.
3. Sunrise and Sunset
Because the earth turns from west to east, the sun appears to rise in the east and set in the west. At sunrise, your place is just turning into the light. At noon, it faces the sun most directly. At sunset, your place is turning away from the sun into darkness. The sun does not move around the earth; we are moving.
| Time | Position of your place |
|---|---|
| sunrise (about 6 a.m. in Ghana) | turning into the sunlight |
| noon | facing the sun most directly |
| sunset (about 6 p.m. in Ghana) | turning away from the sun |
| midnight | facing directly away from the sun |
Ghana is near the equator, so day and night are almost equal all year, about 12 hours each. Countries far from the equator have very long summer days and very short winter days.
Did you know?: When it is noon in Ghana, it is night in Japan, because Japan is on the other side of the earth.
New words
- rotation
- Spinning of the earth on its axis.
- axis
- The imaginary line the earth spins around.
- day
- The time when your part of the earth faces the sun.
- night
- The time when your part of the earth faces away from the sun.
- sunrise
- When the sun appears in the east.
- equator
- An imaginary line around the middle of the earth.
Summary
- The earth spins on its axis from west to east.
- One rotation takes about 24 hours.
- The side facing the sun has day; the other side has night.
- The sun appears to rise in the east and set in the west.
Class activity: Torch and Globe
- In a darkened room, shine a torch (the sun) on a clay globe.
- Mark Ghana with a small paper flag.
- Turn the globe slowly from west to east and note when Ghana has day and night.
You need: Locally made clay globe, Torch, Printed day-and-night picture cards
Exercises
Answer in your exercise book first, then check your answers.
1. What causes day and night?
- A. The earth's rotation
- B. The moon
- C. Clouds
- D. The sun moving
Show answer
Answer: The earth's rotationThe earth spins on its axis.2. How long does one rotation take?
- A. About 24 hours
- B. One week
- C. One month
- D. One year
Show answer
Answer: About 24 hoursThat is one day.3. In which direction does the earth rotate?
- A. West to east
- B. East to west
- C. North to south
- D. South to north
Show answer
Answer: West to eastSo the sun appears in the east.4. The sun moves around the earth each day.
- A. True
- B. False
Show answer
Answer: FalseThe earth rotates.5. Ghana has about 12 hours of daylight all year.
- A. True
- B. False
Show answer
Answer: TrueIt is near the equator.6. The imaginary line the earth spins around is the ______.
Show answer
Answer: axisIt passes through the poles.7. Why does the sun appear to rise in the east?
Show answer
Answer: The earth turns from west to east, so places turn towards the sun from the east.It is the earth that moves.8. When it is day in Ghana, explain why it is night in Japan.
Show answer
Answer: Japan is on the other side of the earth, facing away from the sun at that time.Only half of the earth is lit.
Homework
- Record the times of sunrise and sunset for three days. Write what you notice.