Glossary

Material: Globe, match-sticks, kneaded dough

Procedure:

1. Take a globe. Remove it from the stand.
2. Take at least four matchsticks each of which stands for a person. The head of the matchstick is the person's head.
3. With the help of some kneaded dough, stick these matchsticks at four different locations on it, say on the North Pole¹, in India, in the USA and on the South Pole. Make sure their feet touch the ground.

Some of these people (e.g. people in Australia or on the South Pole) appear to be standing up-side-down. But what does 'DOWN' mean for you? When you are standing on the ground, how do you determine the direction? It is the direction in which a stone dropped from your hand would fall. The stone falls on the ground because the Earth exerts gravitational force on everything near it. Even the atmosphere around the Earth is there because the gases are drawn to the Earth due to its gravitational force. The direction of the gravitational pull is what we call ‘down’. On the Earth, it is always towards the centre of the Earth. The direction exactly opposite to ‘down’ is ‘up’.

Up and down make sense only in those spaces where gravitational force exists. So there is no up or down direction in space. You can hold the globe in any way you like. Usually, it is assumed that the Sun is on one side and the orbit of the Earth is in the horizontal plane. Since the axis of the Earth’s rotation makes an angle of 66.5° with the plane of its orbit, the globe is attached to a stand with its axis tilted by 23.5°. We will learn more about its axis of rotation and orbit in the next two lessons.

Draw the Earth and the people standing at different locations of the Earth.Show the up-down directions for the four people standing on the Earth in the following diagram by using arrows.

Use your notebook for drawing. Please write following on page where you are drawing- The Basic Astronomy Module: Unit 1: Lesson 1: Activity 1 & your Login ID

¹The two poles are the points at which the axis of Earth’s rotation intercepts with its surface.