# NCERT Solution Class 6 Social Science Geography Chapter 3: Motions of the Earth

## Answer the following questions briefly.

### a. What is the angle of inclination of the earth's axis with its orbital plane?

Answer: The angle of inclination of the earth's axis with its orbital plane is 66½°.

### b. Define rotation and revolution.

Rotation: The movement of Earth on its axis is called rotation.

Revolution: The movement of Earth aroud the sun in a fixed orbit is called revolution.

### c. What is a leap year?

Answer: A year with 366 days is called a leap year. Every fourth year is a leap with 29 days in February.

### d. Differentiate between the Summer and Winter Solstice.

Summer Solistice: When the Northern Hemisphere of the Earth experiences summer season and the Southern Hemiphere experiences winter season, it is called summer solistice. The Northern Hemipshere observes summer solistice on 21st June with longest day and shortest night.

Winter Solistice: When the Northern Hemisphere of the Earth experiences winter season and the Southern Hemiphere experiences summer season, it is called winter solistice. The Southern Hemipshere observes winter solistice on 22nd December with longest day and shorter nights.

### e. What is an equinox?

Answer: The direct rays of the sun on 21st March and 23rd September falls on the equator. The whole earth during this time experiences equal days and equal nights.

### f. Why does the Southern Hemisphere experience Winter and Summer Solstice in different time than that of the Northern Hemisphere?

Answer: The Earth is divided into two hemispheres, Northern Hemisphere and Southern Hemisphere. The direct sun rays fall on one side of the Earth due to its spherical shape. The part of the Earth directly facing the sun experiences summer and the other part experences winter. Thus, the Southern Hemisphere experience Winter and Summer Solstice in different time than that of the Northern Hemisphere.

### g. Why do the poles experience about six months day and six months night?

Answer: The inclination of the Earth is the same on its orbit. This inclination keeps one pole facing towards the sun and the other pole facing away from the sun all the six months . Hence, the poles experiences about six months day and six months night.

## 2. Tick the correct answers.

a. The movement of the earth around the sun is known as

1. Rotation
2. Revolution
3. Inclination

Explanation: The movement of Earth aroud the sun in a fixed orbit is called revolution.

b. Direct rays of the sun fall on the equator on

1. 21 March
2. 21 June
3. 22 December

Explanation: The direct rays of the sun on 21st March and 23rd September falls on the equator.

c. Christams is celebrated in summer in

1. Japan
2. India
3. Australia

Explanation: Australia is present in the Southern Hemisphere. In the month of December, Australia experiences longer days and shorter nights., i.e., the summer season.

d. Cycle of the season is caused due to

1. Rotation
2. Revolution
3. Gravitation

Explanation: Seasons changes due to the change in the position of the earth around the sun. The movement of Earth aroud the sun in a fixed orbit is called revolution.

## 3. Fill in the blanks.

1. A leap year has 366 number of days.
2. The daily motion of the earth is rotation.
3. The earth travels around the sun in elliptical orbit.
4. The sun's rays fall vertically on the Tropic of Cancer on 21st June.
5. Days are shorter during winter season.