2nd Class EVS The Solar System The Earth

      The Earth

The earth is the third planet from the Sun. The position of the earth in our solar system is just after the Venus. Structure of our earth looks like an orange and it revolves around the Sun. Our earth takes about 365 days to complete one revolution around the Sun. The earth rotates on its axis also. Night and day on the earth are due to the rotation of the earth on its axis. The revolution of the earth around the Sun causes different seasons.

Look at the following picture of rotation of the earth:

In the picture above, the upper and lower part which are called north and South Pole respectively are the coldest region on the earth. The north and south region on the earth are called polar region. The core of the earth is very hot due to the pressure of its upper surface. The atmosphere of the earth is layered.

Look at the following picture of layers of atmosphere on the earth:

       The Moon

Our earth has one moon (Lunar) which revolves around the earth. The moon of the earth is also called its natural satellite. It completes one revolution around the earth in one month. The moon does not have its own light; therefore, it shines by the sun light. When sun, earth and moon are a lined in a straight line then a natural phenomena called eclipse is occurred. Solar eclipse occurs when the moon passes between the Sun and the earth. In this natural phenomena, the moon covers the Sun partially or fully as seen from the earth.

Look at the following picture of the solar eclipse:

Another natural phenomena that occur due to the rotation of the earth and the moon is lunar eclipse. Lunar eclipse occurs when the shadow of the earth falls on the surface of the moon, or the earth comes between the Sun and the moon.   Look of the following picture of the lunar eclipse:  

      The number of days of a month is related to which one of the following natural phenomena?

(a) Revolution of the moon around the earth

(b) Revolution of the earth around the sun

(c) Rotation of the earth on its axis

(d) All of these

Answer: (a)

Explanation 

The moon takes one month to revolve once around the earth.

Therefore, option (A) is correct and rest of the options is incorrect.

      Consider the following statements:

Statement 1: The upper most layer of the earth's atmosphere is called troposphere.

Statement 2: The lower most layer of the earth's atmosphere is called troposphere.

Which one of the following is correct about the above statements?

(a) Statement 1 is true and 2 is false

(b) Statement 1 is false and 2 is true                                   

(c) Both statements are false

(d) Both statements are true

Answer: (b)                

Explanation 

The lower most layer of the earth's atmosphere is called troposphere.

Therefore, option (B) is correct and rest of the options is incorrect.