Describing the World

Hemispheres

When we learn about different areas of the world, there are different ways of dividing it up. We can divide it according to the globe, by cutting it in half across the middle or from top to bottom, these are called hemispheres. We can divide it according to land areas, or continents. It can also be divided according to languages spoken, climate, environment and economy. In this article we are going to look at the hemispheres.

The world is a sphere. It is shaped like a ball. The best way to represent the world is not by a map, but by a globe. How can we explain where anything is on the globe? We could say it is next to something else, or at the top or bottom, or even on the left or right, but these are not geographical terms. In geographical terms we have to describe position by using a compass.

The main points, or cardinal points, on a compass are North, South, East and West. The globe can be divided into half across the middle, or from top to bottom. Each of these halves is called a hemisphere. The word hemisphere means half (hemi) of a sphere. Because we can divide the ball two different ways, we can have four different hemispheres. Right and left, or top and bottom. Think about the cardinal points of the compass. What do you think we are going to call the hemispheres? If you are confused about where North, South, East and West are, go back and read the article on
compasses.

Activity #1

For this activity you need two oranges and a sharp knife.

Cut the first orange in half from top to bottom.
Cut the second one across the middle.
These are the two different ways you can divide the globe into hemispheres.
You have four hemispheres.

This can be a little confusing. Everyone knows that if you divide something into half, you only get two pieces. What you have to remember is that you can divide it into half either way, so you can make 4 hemispheres from a sphere. If you actually cut it with a knife, then you need two spheres to get your 4 hemispheres, but if you imagine the hemispheres, you can imagine all 4 on the same sphere.

Activity #2

For this activity you will need a plain colored ball, and a marker pen.

Take the ball and pen.
Put an X at the top of the ball and an O at the bottom.
Now draw a line from the X to the O across the front of the ball.
Mark the front of the ball with an F.
On the opposite side continue the line up from the O to the X.
Now you have divided the ball into two halves, left and right.
Find the middle of both lines. Mark them.
Draw a line around the center of the ball, through the points you marked.
Now you have a top and a bottom half.

Go back to the points of the compass. Do you think you can name your hemispheres? The top and bottom ones are easy. The top is North, and the bottom is South. With the front of the ball facing you, West is on the left and East is on the right (remember they spell WE). Write the letter in each of the areas.
Don’t forget that because you have marked all 4 hemispheres on the ball, you have divided your ball into 4, so 2 pieces will need each of the letters. Notice that each of the areas has two letters, either N or S and W or E.

Now we need to use a little grammar here. North, South, East and West are nouns, but we need adjectives to describe which hemisphere is which. So we call them the Northern Hemisphere, the Southern Hemisphere, the Eastern Hemisphere and the Western Hemisphere.

Look at your ball again.
Close your eyes, turn the ball around in your hands, and then place the pen on the ball, keeping your eyes closed.
Open your eyes and see where you placed the mark. Notice that it is in two hemispheres. If you used your hand instead of the pen, it could even fall into three hemispheres.
Which two hemispheres did your mark land in?

Now, put your ball away in another room and see if you can answer these questions:

1. How many hemispheres are there?
2. What are they called?
3. Which hemisphere is at the bottom of the ball?
4. Which is at the top?

These questions are a little more difficult, you may need to use the ball to answer these:

1. With the front of the ball facing you, which hemisphere is on the left?
2. What happens when you turn the ball around so that the back is facing you?
3. Now which hemisphere is on the left?

Don’t erase the marks on the ball, we are going to use it again in the next article

Bonus Activity for Older Students

Do you know that the lines you have drawn have geographical names? Do you know what they are?

The line running around the middle of the globe, dividing the Northern and Southern Hemispheres is called the Equator. It is shown on maps as 0 degrees Latitude.

The line dividing the globe into the Eastern and Western Hemispheres is actually two geographical lines. The one running down the front of the globe is known as the Greenwich Meridian. It passes through the Greenwich Observatory in London, and is measured as 0 degrees longitude.

The line dividing the globe into the Eastern and Western Hemispheres on the back of the globe is called the International Dateline. It is measured at 180 degrees West or East. It doesn’t matter which way you go around the globe, it is 180 degrees either way round.

When you placed the random mark on the ball, it fell into two hemispheres. There are two named places on earth that do not fall into 2 hemispheres. Can you think what they are?

Theoretically, any point that lies on the International Dateline, Greenwich Meridian or Equator, fall in one hemisphere only. It is also theoretically possible for a ship to be in all four hemispheres at the same time, if it was centered exactly over the equator on the Greenwich Meridian or International Dateline (both these points lie in the ocean).

Now answer these questions:

1. What is the line called which divides the Northern and Southern Hemispheres.
2. Can you name one country this line passes through?
3. Name the two lines dividing the globe into Eastern and Western Hemispheres.
4. Which two hemispheres do you live in?