Rotation and Revolution of Earth

What is the difference between Rotation and Revolution of earth? How many times the earth takes to revolve around the Sun? Your all doubt will be cleared in this post. 

The Earth moves in space in two distinct ways Rotation and Revolution.

  1. It rotates on its own axis from West to East once in every 24 hours. It causes day and night.
  2. It revolves around the Sun in an orbit once in every 365 days. It causes the seasons and the year. Rotation of Earth

Rotation of Earth

  • It is the spinning movement of the earth from west to east on its axis once in 24 hours. The axis is an imaginary line joining the two poles.
rotation of earth
  • The phenomenon of day and night is the most important consequence of the rotation. The one half of the earth facing the sun experiences daylight, while the other half away from the sun experiences constant tit night.
  • The rotational speed at the equator is Maximum (1667 km/hours) and then decreases towards the poles, where it is zero.

The rotation of the Earth has the following implications such as

  1. Causation of day and night.
  2. Change in the direction of winds and ocean currents.
  3. Rise and fall of tides every day.
  4. A difference of 1 hour between the two meridians which are 15º apart.

Revolution of Earth

  • The movement of the earth around the sun is a fixed elliptical path or orbit. It is called revolution, completed by the earth in 365 1/4 days. This one fourth day of four consecutive years is added as an extra day in the fourth year as 29th February, making that year a ‘leap year.
  • Due to the elliptical shapes of the orbit, the earth is closest to the sun on January 3 (at a distance of about 147 million km) and is said to be at Perihelion.
  • Around July 4 the earth is at farthest from the sun (152 million km away) and is known to be at apehelion.
  • Average speed of the earth’s revolution is 107,000 km/hour (29.72 km/second).
  • The revolution of the earth coupled with the tilt of the earth’s axis causes different seasons to occur on the earth.

The revolution of Earth result in

  1. Changes of Season.
  2. Variation of the length of the days and nights at different times of the year.
  3. Shifting of the wind belts.
revolution of Earth

Varying Lengths of Day and Night

  • Owing to revolution and constant angle of inclination of the earth’s axis, the sun is vertically overhead at the tropic of cancer on 21 June each year.
  • Towards the North Pole, the length of daytime increases, and beyond 6612 °N the region has 24 hours light for six months.
  • On 21st June, the Northern Hemisphere has its longest day and shortest night. This is known as Summer Solstice.
  • By 22nd December, exactly the same conditions prevail in the Southern Hemisphere when the Sun is vertically overhead at the tropic of Capricorn. This is Winter Solstice, when the Southern Hemisphere experiences its longest day and shortest night.
  • On 21st March and 23rd September, the sun is directly over the equator and all parts of the world have equal days and nights. Hence the 21st March and 23rd September are called Vernal and Autumnal Equinoxes respectively.

The Moon

  • The Moon is the only one satellite of our Earth.
  • We can see only 59% of the Moon’s surface.
  • The circumference of the moon is 11000 km.
  • The distance between earth and moon is about 382200km.
  •  Our moon is about ¼ of the size of earth.
  • It takes 27 days, 7 hours, 43 minutes and 11.47 seconds to complete one revolution around the earth.
  • The moon has no atmosphere.
  • Its gravitational power is too weak (1/6th of the Earth).
  • The highest mountain on the surface of the moon: Leibnitz (Located in the south pole of the moon)

Super Moon

  • Super moon also called Perigee Moon, it occurs when the moon is nearest the earth.
  • It appears 30% larger.

Blue Moon

  • It is the occurrence of the two full moons in a month.
  • Blue Moon was seen in the year 2015 and 2018.

Eclipses

  • An eclipse occurs when the Sun, Moon and Earth are in a straight line.
  • There are two types of eclipses : Lunar Eclipse and Solar Eclipse

Lunar Eclipse

Lunar Eclipse
  • It occurs when the earth comes between the sun and the moon, and the moon is not able to get sunlight due to the shadow of the earth cast on it.
  • A Lunar eclipse occurs always on full moon day, but not on every full moon, since the orbital planes of the earth and moon are inclined at 5 to each other.

Solar Eclipse

Solar eclipse
  • When the moon comes between the Sun and Earth.
  • It can be partial or total.
  • It will happen only on a new Moon day when the Moon is in line with the Sun.
  • A solar Eclipse does not occur on every new Moon day.

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