Motions of the Earth Question Answers: NCERT Class 6 Social Science - The Earth Our Habitat

(a) The angle of inclination of the Earth’s axis with its orbital plane is 66 ½◦.

(b) Rotation:

• The movement of the Earth on its axis is called rotation.
• The Earth takes 24 hours to complete one rotation.
• Days and nights are caused due to rotation of the Earth.

Revolution:

• The movement of the Earth around the sun in a fixed path or the orbit is called revolution.
• The Earth takes 365 days six hours to complete one revolution.
• Seasons are caused due to revolution of the Earth.

(c) A year with 366 days is called leap year. It occurs once in four years on the month of February and it is 29^th day of that month. It is also called intercalary year. The Earth do not take exact 365 days in an year and 24 hours in a day, so we add them as one extra day once in four year.

(d) Differences between summer and winter solstice are as follows:

(e) On 23^rd September and 21^st March, the rays of sun directly falls on the equator. So, at that position neither of the poles are tilted. So at that specific or we can say a particular day the earth experiences equal days and nights and this is called as equinox.

(f) The Southern Hemisphere experience winter and summers solstice in different times than that of the Northern Hemisphere because:

1. Southern Hemisphere is tilted towards the Sun on 22^nd December, so summer Solstice is there in Southern Hemisphere. At that time Winter Solstice is in Northern Hemisphere.
2. In 21^st June the Northern Hemisphere is tilted towards the Sun, so Summer Solstice is there and Winter Solstice is in the Southern Hemisphere.

(g) The poles experiences about six months day and six months night because:

1. When Northern Hemisphere is tilted towards the Sun, The North Pole remains in the light for the whole day. This position remains for six months from 21^st March- 23^rd September.
2. On the same time Southern Hemisphere is away from the Sun, the South Pole does not get light for six months. So it experiences night for six months and vice versa.

(a) (ii) Revolution

Seasons are caused due to revolution of the earth around the sun. Revolution is a movement of earth near the sun on a fixed path (orbit) in an elliptical way.

(b) (i) 21 March

On 21^st March, the rays of sun directly fall on the equator. So at that particular day, the earth is not tilted towards any pole and experiences an equinox (equal days and nights).

(c) (iii) Australia

As Australia is present in the Southern Hemisphere so during December Australia experience summer due to revolution. And, in same manner at that time the Northern hemisphere experiences winter.

(d) (ii) Revolution

As earth revolves around the sun in an elliptical path, so it cause change in season.

(a) 29

There are 29 days in February once in every four year which is an additional day of the year, also called the leap year.

(b) Rotation

Rotation is the daily motion of the earth. The earth completes one rotation in 24 hours. Days and nights are cause due to rotation of the earth.

(c) Elliptical

Elliptical shape is something like oval. The orbit of the planets is an elliptical path. It is not a complete circle.

(d) Cancer

On 21^st June, the Northern Hemisphere gets tilted towards the sun. So, the rays of sun directly fall on the Tropic of Cancer (23½◦N).

(e) Winter

Due to summer solstice, the days get shorter and nights get longer than the days.