Revolution

At the same time that the Earth spins on its axis, it also orbits, or revolves around the Sun. This movement is called revolution.

It takes 365¼ days (one year) to revolve around the sun. We consider a year as consisting of 365 days only and ignore six hours for the sake of convenience.
Six hours saved every year are added to make one day (24 hours) over a span of four years. This surplus day is added to the month of February.
Thus every fourth year, February is of 29 days instead of 28 days. Such a year with 366 days is called a leap year.
The gravitational pull of the Sun keeps Earth and the other planets in orbit around the star. Like the other planets, Earth’s orbital path is an ellipse so the planet is sometimes farther away from the Sun than at other times.
The closest Earth gets to the Sun each year is at perihelion (147 million km) on about January 3rd and the furthest is at aphelion (152 million km) on July 4th.
Earth’s elliptical orbit has nothing to do with Earth’s seasons.
During one revolution around the Sun, Earth travels at an average distance of about 150 million km.
Earth revolves around the Sun at an average speed of about 27 km (17 mi) per second, but the speed is not constant.
The planet moves slower when it is at aphelion and faster when it is at perihelion.
The reason the Earth (or any planet) has seasons is that Earth is tilted 23 1/2oon its axis.
During the Northern Hemisphere summer the North Pole points toward the Sun, and in the Northern Hemisphere winter the North Pole is tilted away from 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 21st 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.
The opposite is the case on 21st March, when it is spring in the Northern Hemisphere and autumn in the Southern Hemisphere.

Effects of revolution

Revolution along with the earth’s tilted axis leads to changing seasons across the hemispheres.
The speed of the Earth’s revolution has influenced the state of the Earth. On account of the speed of pivot, a diffusive power is made which prompts the straightening of the Earth at shafts and protruding at the middle.
The Earth’s revolution influences the development of water in the seas. The tides are redirected because of the turn.
The speed of revolution additionally influences the development of the breeze. Because of revolution, winds and the sea flow redirect to one side in the Northern Hemisphere and to one side in the Southern Hemisphere.