NCERT Class 6 Geography Chapter 3: Motions of the Earth Complete Notes Part 1

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Motions of the Earth

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Now most important are two motion we familiar with the rotation and revolution. Now to explain that considered sun and I have small size earth here. Which is considered as a blue planet. So, you have the sun and the earth if I say earth is rotating on in axis that means it rotating on single axis as a point we have understand and we have discussed in the globe. That motion is known as a rotation.

However if the earth moves around in the fixed path we call this revolution. Now because of rotation you have day and night phenomena that occurs and because of revolution season occurs.

Now understand that in detail as move forward, first thing that will understand today is the rotation.

Rotation

  • Movement of earth on its axis – 24 hours - Earth day

Image of Erath

Image of Erath

As I said it is the movement around the axis, you have axis of the earth and movement around the axis that would be considered as a rotation. Earth takes 24 hours to complete one rotation and that is known as the Earth day. Now moving forward you have revolution.

Revolution

  • Movement of earth around sun in fixed path: 365 ¼ days

  • Extra 6 hours added for 4 years – 1 day extra – leap year

Image of sun and Earth for understanding Revolution

Image of Sun and Earth for Understanding Revolution

As I said revolution is moving of earth around the sun. So sun here is stationary and you have the earth that is moving around the sun and around the earth you have moving moon. So, you have earth moving around in elliptical path around the sun that is known as revolution.

As said revolution causes season and this is the fixed path and which is moved and that takes days. You have one day in 24 hours.

Now what I do is add 6 hours 4 times and I get 1 day. That’s 24 hours again. So what happened is for 3 years you have 365 days and you add 6 hours and every 4 years you have leap year (with extra day). Where you increased day by 1 and you have 366 days.

Now when we calculate leap year. You say it should divided by 4 but if it is in thousand it should be divided by 400. So that the way to calculate whether year is a leap year or not. So for leap year you have 366 days and for normal year you have 365 days. So this is the basic phenomena of revolution.