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`color{green}(โข)` There are two types of earth motions namely rotation and revolution.
`color{green}(โข)` Rotation is the movement of the earth on its axis.
`color{green}(โข)` The movement of the earth around the sun in a fixed path or orbit is called Revolution.
`color{green}(โข)` The axis of the earth which is an imaginary line, makes an angle of 66ยฝยฐ with its orbital plane.
`color{green}(โข)` The plane formed by the orbit is known as the orbital plane.
`color{green}(โข)` The earth receives light from the sun.
`color{green}(โข)` Due to the spherical shape of the earth, only half of it gets light from the sun at a time (Figure 3.2).
`color{green}(โข)` The portion facing the sun experiences day while the other half away from the sun experiences night.
`color{green}(โข)` The circle that divides the day from night on the globe is called the circle of illumination.
`color{green}(โข)` This circle does not coincide with the axis as you see in the Figure 3.2.
`color{green}(โข)` The earth takes about 24 hours to complete one rotation around its axis.
`color{green}(โข)` The period of rotation is known as the earthday. This is the daily motion of the earth.
`color{green}(โข)` What would happen if the earth did not rotate? The portion of the earth facing the sun would always experience day, thus bringing continuous warmth to the region.
`color{green}(โข)` The other half would remain in darkness and be freezing cold all the time.
`color{green}(โข)` Life would not have been possible in such extreme conditions.
`color{green}(โข)` The second motion of the earth around the sun in its orbit is called revolution.
`color{green}(โข)` It takes 365ยผ days (one year) to revolve around the sun.
`color{green}(โข)` We consider a year as consisting of 365 days only and ignore six hours for the sake of convenience.
`color{green}(โข)` Six hours saved every year are added to make one day (24 hours) over a span of four years.
`color{green}(โข)` This surplus day is added to the month of February.
`color{green}(โข)` Thus every fourth year, February is of 29 days instead of 28 days.
`color{green}(โข)` Such a year with 366 days is called a leap year. Find out when will the next leap year be?
`color{green}(โข)` From the Figure 3.3, it is clear that the earth is going around the sun in an elliptical orbit.
`color{green}(โข)` Notice that throughout its orbit, the earth is inclined in the same direction.
`color{green}(โข)` A year is usually divided into summer, winter, spring and autumn seasons.
`color{green}(โข)` Seasons change due to the change in the position of the earth around the sun.
`color{green}(โข)` Rotation is the movement of the earth on its axis.
`color{green}(โข)` The movement of the earth around the sun in a fixed path or orbit is called Revolution.
`color{green}(โข)` The axis of the earth which is an imaginary line, makes an angle of 66ยฝยฐ with its orbital plane.
`color{green}(โข)` The plane formed by the orbit is known as the orbital plane.
`color{green}(โข)` The earth receives light from the sun.
`color{green}(โข)` Due to the spherical shape of the earth, only half of it gets light from the sun at a time (Figure 3.2).
`color{green}(โข)` The portion facing the sun experiences day while the other half away from the sun experiences night.
`color{green}(โข)` The circle that divides the day from night on the globe is called the circle of illumination.
`color{green}(โข)` This circle does not coincide with the axis as you see in the Figure 3.2.
`color{green}(โข)` The earth takes about 24 hours to complete one rotation around its axis.
`color{green}(โข)` The period of rotation is known as the earthday. This is the daily motion of the earth.
`color{green}(โข)` What would happen if the earth did not rotate? The portion of the earth facing the sun would always experience day, thus bringing continuous warmth to the region.
`color{green}(โข)` The other half would remain in darkness and be freezing cold all the time.
`color{green}(โข)` Life would not have been possible in such extreme conditions.
`color{green}(โข)` The second motion of the earth around the sun in its orbit is called revolution.
`color{green}(โข)` It takes 365ยผ days (one year) to revolve around the sun.
`color{green}(โข)` We consider a year as consisting of 365 days only and ignore six hours for the sake of convenience.
`color{green}(โข)` Six hours saved every year are added to make one day (24 hours) over a span of four years.
`color{green}(โข)` This surplus day is added to the month of February.
`color{green}(โข)` Thus every fourth year, February is of 29 days instead of 28 days.
`color{green}(โข)` Such a year with 366 days is called a leap year. Find out when will the next leap year be?
`color{green}(โข)` From the Figure 3.3, it is clear that the earth is going around the sun in an elliptical orbit.
`color{green}(โข)` Notice that throughout its orbit, the earth is inclined in the same direction.
`color{green}(โข)` A year is usually divided into summer, winter, spring and autumn seasons.
`color{green}(โข)` Seasons change due to the change in the position of the earth around the sun.
