You are here for Motions of the Earth Class 6 note. Please read thoroughly to get all the knowledge of Chapter 3 class 6 Geography “Motions of the Earth”.
You all may be wondering about how day and night happens and how we get summers, winters and other seasons around the year. These are result of motions of earth which we already know at a basic level.
Motions of the Earth class 6 notes
As we all know the earth has two type of motion.
First, Rotation is the motion of earth on own axis and Second, Revolution is the movement of earth around the sun in a fixed path called as orbit.
Orbital plane is the plane in which earth’s revolution path is located. The path of earth’s revolution is an ellipse. The earth axis which is an imaginary line; makes an angle of 66o 30’ with the orbital plane.
Rotation & Circle of Illumination
We know that earth receives its light and heat from the sun and earth has spherical shape. therefore we experience day at one side and night at another side.
The circle that divide the day with night, called circle of illumination. This circle of illumination always makes an angle of 23o 30’ from the earth’s axis. The earth takes 24 hours to rotate around its axis and this period is the earthday.
You may be wondering that what if the earth did not rotate?
Well in that condition one side of earth always experience light and another side always experience darkness. Therefore, in such case life would not be possible.
Revolution of the Earth
The second motion of earth is Revolution around the sun. It takes 365.25 days to complete its one revolution around the sun and complete it’s one year.
In our calendars we consider a year as 365 days and after every 4 years we name the year as leap year which has 366 days. This one day which is extra in leap year is added to the month of February, thus every fourth year February is of 29 days instead of 28.
A year is divided into summer, winter, spring, and autumn seasons. The seasons of the earth change due to the change in the position of the earth with its revolution.
Summer Solstice is the position of the earth at which North pole of the earth is inclined towards sun and places beyond the Arctic circle are in continuous daylight. 21st June is the day on which longest day and shortest night occur in the Northern region similarly, reverse in the Southern region.
Winter Solstice is the position of the earth at which the South Pole is inclined towards the sun. Therefore like Arctic circle in summer solstice, Antarctic circle experience continuous daylight. 22nd December is the day when the longest day and shortest night occur in the southern hemisphere and similarly, reverse in the north hemisphere.
Equinox is the position of earth at which neither of the poles is inclined towards sun. This position of the earth comes twice a year and equator experience direct rays of the sun. On 21st March and 23rd September earth experience equal day and night.
In conclusion, we understood that the two rotations of earth come to us with the two major changes on our earth which are – 1st is the day and night by the rotations along its axis and 2nd is the seasons which is the result of revolution of earth around the sun.