We are living in the house. House is on earth.
The earth is very big. To study the earth we have to make a model of the earth. This model is called the globe.
The globe is a hollow sphere on which the map of the earth is pasted or printed. Even on the globe we cannot see the whole earth. To see the earth on the globe we have to rotate it on its axis.
Maps and atlas
We can draw the two halves of the globe on a flat surface. This is called map.
Maps can be big or small.
A book of maps is called an atlas.
The four directions
There are four directions. These are east, west, north and south. When we see a map, the top of the map always shows the north, east is on our right, and west on the left and south is towards the bottom.
· The age of the earth is at least 4 ½ billion years
· The earth rotates once every 23 hours, 56 minutes and 4.09 seconds
· The earth is not a perfect sphere. It is slightly flat at the top and at the bottom.
· The atmosphere of the earth is roughly 2000 kilometers from the sun
· The nine planets of our solar system are mercury, Venus earth, mars, Jupiter, Saturn, Uranus, Neptune and Pluto
· Pluto is the smallest planet of our solar system
· Jupiter is the largest planet our solar system
Planet- The celestial bodies orbiting around a star
Atmosphere – The layer of air that surrounds the earth
Satellites – Natural heavenly bodies and man- made machines that revolve around the planets
Sky – Atmosphere and outer space as seen from the earth
Horizon – an imaginary line where land seem to meet the sky
· Air and water support life on the earth
· The earth is home of all living beings
· Horizon is where land and sky seem to meet
A) The meeting of land and sea is called coast
B) The layer of air surrounding the earth is called atmosphere
Let us meet
It was earlier believed that the sun moves around the earth. Nicolas Copernicus a polish astronomer disproved this theory in 1543. The main point of Copernicus system is: the sun and stars are motionless. The earth rotates on its axis taking 24 fours to complete one rotation. The earth and planets revolve around the sun. The moon revolves around the earth.