Good relations from the sun to the earth in many sectors. We are blinders in the night. Sun rays rises in the day.

A man is in the sunlight. Carefully observe the position of the sun and the shadows of the man.

The length and the direction of the shadow change with changes in position and direction of the source of light. You will notice that as the sun appears to move across the sky from east to west say along A.B.C.D.E position the shows of the man also change accordingly, say A,’B,’C’,D’ and E’ respectively.

At noon, the shadow is very short. But in the morning and in the evening it is long. Why? At noon the sun is directly overhead. So, the sun rays fall vertically on the body. Hence, the shadow is very short. In the mornings and in the evenings, the run rays fall an inclined position. So, the shadows are long.

Villagers know the time by observing shadows. An apparatus which tells us the time from the length and the position of the shadows is called a `Sundial’. Sundials are still at Jantar Mantar in Delhi and in Jaipur.

Example

Take a long stick or an iron rod. Fix it vertically in the open ground. Mark its shadow just after the sunrise. Continue the same for every one hour until the sunset. Note the length and direction of the shadow for each observation. Record your observations in a table given.

Eclipses

When the planets or satellites block the light of the sun, their, shadows are formed on other planets or satellites. These shadows are called `eclipses’.

In olden days, people considered eclipses bad omen.

There are two types of eclipses. They are:

1) The solar eclipse and

2) The lunar eclipse.