1. What are the movement of the Earth?

    The Earth has two movements. They are :

       1. Rotation
       2. Revolution

2. What is rotation?

Earth moves around its own axis from West to East at a speed of 1610 kilometers per hour. The movement is called rotation. The Earth takes 24 hours to complete one rotation. It causes day and night.

3. What is axis?

An imaginary line which connects the North pole and the South pole through the centre of the Earth is called the axis.

4. What are the poles?

The two end points of the axis of rotation are called the poles. The northern point is called ' North pole' and the southern point is called the ' South pole'.

5. What is the angle of inclination of the Earth's axis with its orbital plane?

The angle of inclination of the Earth's axis with its orbital plane is 66 and half degree which means the Earth remains tilted to one side while it revolve around the Sun at an angle of 66 and half degree.

6. What is revolution?

The Earth moves around the Sun while moving around its axis. This movement is called revolution. The Earth takes 365 days and 6 hours to complete one revolution. It causes seasons.

7. What is orbit?

The fixed and and regular path through which Earth revolves around the Sun is called orbit. This orbit is elliptical in shape. The length of the Earth's orbit is 965 million kilometers.

8. What is leap year?

Earth takes one year to complete one revolution. Strictly speaking, it takes 365 1/4 days. A normal year consists of 365 days only. The remaining one fourth of the days is added once in four years ,and the year is known as leap year. Hence a leap year consists of 366 days.

9. Why does the Southern hemisphere experiences winter and summer solstice in different times than that of Northern hemisphere?

The seasons in Southern hemisphere and Northern hemisphere are exactly the opposite.

10. What is elliptical in shape?

The distance between the Earth and the Sun is not constant as the Earth's orbital path is elliptical in shape.

11. What is aphelion?

The farthest position of the Earth from the Sun is known as the aphelion.

12. What is perihelion?

The closest position of the Earth from the Sun is known as the perihelion.

13. Why do the poles experience six months day and six months night?

When the rays of the sun fall directly on the Tropic of cancer (21^st June), the areas near the south pole receive less heat .The North pole is inclined towards the Sun and places beyond the Arctic circle experience continuous day light . At this time, the southern hemisphere has the opposite season. The nights are long and areas beyond Antarctic circle get continuous night. The reverse will happen on 22^nd December.

14. What are equinox?

The Sun appears vertically overhead at noon on the equator on March 21 and September 23, the length of day and nights are equal all over the world on these two days. Hence these days are known as equinox.

15. Describe the causes of Earth's revolution.

Earth revolution causes variation in day and night durations and seasons. The distance between the Earth and the Sun is not constant as the Earth 's orbital path is elliptical in shape.