## Class 6 Geography Chapter 3 Notes:- Motion Of The Earth

In this post, we provide Class 6 Geography Chapter 3 Notes:- Motion Of The Earth. These notes are based on the CBSE NCERT Books. The Earth has two types of motion rotation and revolution.

In this post, we discuss various types of motion of the earth and their outcome. By the end of this post (Class 6th Geography Chapter 3 Notes:- Motion Of The Earth notes), you will learn the motion of the earth, Summer Solstice, Winter solstice, and Equinox.

## Motion Of The Earth

The earth has two types of motions,

• Rotation:- Rotation is the movement of the earth on its axis.
• Revolution:- Revolution is the movement of the earth around the sun in a fixed path or orbit.

### Rotation

• An imaginary line which is drawn from the north pole to the south pole is called the axis.
• The axis makes an angle of 66½° with its orbital plane.

The earth receives light from the Sun. Due to its spherical shape, only one half gets light at a time. The person facing the sun experiences the day while the other half away from the sun experiences the night.

The circle that divides the day from night on the globe is called the circle of illumination.

The earth takes about 24 hours to complete one rotation around its axis.

The period of rotation is known as Earth Day. This is the daily motion of the earth.

What would happen If Earth did not rotate?

the portion of the earth facing the sun would always experience a day thus bringing continuous warmth to the reason. The other half would remain in darkness and be freezing cold all the time. Type would not have been possible in such extreme conditions.

### Revolution

The motion of the earth around the sun in its orbit is called revolution.

• Orbit- a fixed path in which Earth revolves around the Sun is called Orbit.
• The plane formed by the orbit is called an orbital plane.
• The Earth revolves around the sun in an elliptical Orbit.
• It takes 365 days to revolve around the sun.
• We consider a year as consisting of 365 days only and ignore 6 hours.
• These 6 hours become 24 hours ( one day) after 4 years.
• This surplus day is added to the month of February thus every 4th year February is 29 days instead of 28 days.
• The year which has 366 days is called a leap year.

A year is usually divided into four seasons:- summer, winter, spring, and autumn.

Seasons change due to the change in the position of the earth around the sun.

### Summer Solstice

On 21st June, the Northern Hemisphere is tilted towards the sun. The rays of the sun fall directly on the Tropic of Cancer. As a result, these areas receive more heat. The areas near the poles receive less heat as the rays of the sun are slanting. The North Pole is inclined towards the sun and the places beyond the Arctic Circle experience continuous daylight for about six months.

Since a large portion of the Northern Hemisphere is getting light from the sun, it is summer in the regions north of the equator. The longest day and the shortest night at these places occur on 21 st June. At this time in the Southern Hemisphere, all these conditions are reversed. It is winter season there. The nights are longer than the days. This position of the earth is called the Summer Solstice.

### Winter solstice

On 22nd December, the Tropic of Capricorn receives direct rays of the sun as the South Pole tilts towards it. As the sun’s rays fall vertically at the Tropic of Capricorn (23½° S), a larger portion of the Southern Hemisphere gets light. Therefore, it is summer in the Southern Hemisphere with longer days and shorter nights. The reverse happens in the Northern Hemisphere. This position of the earth is called the Winter Solstice.

### Equinox

On 21st  March and September 23rd, direct rays of the sun fall on the equator. At this position, neither of the poles is tilted towards the sun; so, the whole earth experiences equal days and equal nights. This is called an equinox.

On 23rd September it is autumn season in the Northern hemisphere and spring season in the southern hemisphere.

All 21st March when it is Spring in the Northern hemisphere and autumn in the southern hemisphere.

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