My Science School

Light travels faster than anything else we know of. The Sun is about 150 million kilometres away from Earth and yet its light takes only about eight minutes to reach us! Some of the stars are so far away that their light takes many years to reach us. We do not see them as they are, but as they were hundreds, thousands or even millions of years ago!

Sometimes you can see rays of light from the Sun as they light up dust particles in the air. The rays do not bend — they seem to travel in straight lines.

Light travels in straight lines

Light from the torch travels through the holes in the first screen. But only the rays travelling through the centre hole have a straight path through all three screens. Light rays travel in straight line.

Our most important source of light is the Sun. The Sun has an enormous amount of energy which is given out in the form of heat — at its centre, the temperature of the Sun is about 13 million degrees centigrade! It is some of this energy which reaches us as light.

Since the Earth spins around once every 24 hours, we only face the Sun part of the time — the time we call ‘day’. At night, light from the Sun can no longer reach us. But even at night there is some light. The stars, like the Sun, produce light. The Moon also provides light. But the Moon has no light of its own — it simply reflects light which has reached it from the Sun.

            Electric lights enable us to see well at night. At night, we see how the Moon reflects the Sun’s light.

Our sense of sight is one of our most important links with the world. We can see thousands of colours and shapes which help us to recognize the people, places and things around us. But our eyes are limited. Not until the discovery of lenses were we able to see the things which were either too small or too far away for our eyes to focus on.

Telescopes enable us to see faraway objects such as galaxies.

Lenses in microscopes allow us to see tiny forms of life, helping us to understand how living things function. And lenses in telescopes have enabled us to understand something of the solar system, and the universe, of which we are a tiny part. You will learn how a special type of light, laser light is changing our lives.

Picture Credit : Google