Motions Of The Earth

 Part I

Qts  1 What do you mean by the inclination of the earth's axis?

1.The tilted position of the Earth's axis is known as inclination of the Earth's axis. 

2.The Earth's rotation axis makes an angle of about 66.5° with the plane of its orbit around the Sun or about 23.5° from the perpendicular to the elliptical plane. 

3.This inclination is the reason we experience different seasons on the Earth.

Qts 2 What are the effects of the earth's rotation

1.Rotation creates a diurnal cycle of light and darkness, i.e. day and night

2.Rotation causes tides, i.e. rise and fall of the sea level twice a day.

3.Rotation causes sunrise in the east and sunset in the west.

Qts 3 Why does February have 29 days after every 4 years?

1.The Earth revolves around the Sun in anticlockwise direction and it takes about 365 days and 6 hours to complete one revolution. 

2.These extra 6 hours are added every year for the next four years to create a total of 24 hours or one more day in February. 

3. This extra day in February comes after every four years and the year in which it occurs is known as the leap year; it has 366 days in total.

Qts 4. What are the effects of revolution?

1.Variation in the lengths of days and night

2.Slanting or vertical sunrays

3. Occurrence of various seasons (spring, summer, autumn and winter) 

4. Movement of the Sun between the Tropic of Cancer and the Tropic of Capricorn

Qts  5. Name the two factors responsible for the occurrence of seasons.

1. The Earth rotates on its own axis and it is tilted at an angle of 23.5° with respect to its orbital plane; this causes the occurrence of seasons.

2. The revolution of the Earth around the Sun, which requires 365 days and 6 hours, in an elliptical orbit also causes the change in seasons.

Qts 6 Explain difference between rotation and resolution

I. Rotation

1.The Earth takes 24 hours to complete one rotation

2.The Earth rotates on its axis. 

3. The rotation of the Earth causes day and night.

II Resolution 

1. The Earth takes around 365 days and 6 hours to complete one revolution around the Sun

2. The Earth revolves around the Sun in an elliptical orbit.

3. The revolution of the Earth causes the occurrence of seasons.

Qts 7 Explain Vertical rays of the sun and slanting rays of the sun

I. Vertical Rays

1.These are concentrated rays and carry more heat.

2. These rays spread over a very small area on the Earth

3. The part of the Earth tilted towards the Sun receives vertical rays.

II. Slanting Rays

1.These are not concentrated and carry less heat.

2. These rays spread over a large area on the Earth.

3. The part of the Earth tilted away from the Sun receives slanting rays.

Qts 8 What is the reason for alternate days and nights.

1.This is because the Earth rotates on its axis and completes one rotation in 24 hours. 

2. During this rotation, sunrays fall on half of the spinning Earth and this half of the Earth experiences day. 

3. The other darker side of the Earth experiences night during this time.

4. With each spin, the Earth moves from darkness to light and vice versa

Qts 9 Why  Days and nights are not equal in length.

1.The variation in the lengths of days and nights occurs because the Earth revolves around the Sun, with its axis always inclined at an angle of 66.5°.

2. This causes longer days and shorter nights in summer in the southern hemisphere.

3. This variation between the lengths of  days and nights increases with increasing distance from the Equator to the poles.

Qts10  Why 21st June is the longest day in the Northern Hemisphere.

1. On 21 June, the Northern Hemisphere is inclined towards the Sun. 

2.The rays of the Sun fall directly on the Tropic of Cancer, causing summer in the Northern Hemisphere and winter in the Southern Hemisphere.

3. Because of this, we experience the longest day and the shortest night of the year on 21 June. 

Qts 11 Why On 21st March and 23rd September days and nights are equal all over the world.

1.On 21 March and 23 September, the Sun shines vertically on the Equator; therefore, all places on the Earth experience equal days and equal nights.

2.On 21 March, the Northern Hemisphere has spring, while the Southern Hemisphere has autumn.

3. On 23 September, the Northern Hemisphere has autumn, while the Southern Hemisphere has spring.

Qts 12. The angle which the earth's axis makes with the plane of the earth's orbit is

1.Twenty three and half degree

2.The Earth's axis is an imaginary line joining the North Pole and the South Pole. 

3.This axis is tilted at an angle of 23½° with respect to the plane of the Earth's orbit. 

4.This tilt is also known as the inclination of the Earth's axis.

Qts 13 The time of the day just before sunrise is known as

Dawn  is the time just before sunrise. During this time, the sky starts getting filled with the Sun's glow and the rays of the Sun start piercing the darkness.

Qts 14.  During summer the poles have continuous daylight for

1. 6 Months 

2.During summer, both the poles, i.e. the North and South Poles, experience continuous daylight for a period of six months; during winter, both the poles experience continuous darkness for a period of six months.

Qts 15 22nd December is the shortest day in the

1. Northern Hemisphere 

2. On 22 December, the Northern Hemisphere turns away from the Sun and experiences the shortest day. On the contrary, at this time, the Southern Hemisphere inclines towards the Sun and therefore experiences the longest day.