Difference Between Rotational and Translational Motion

Rotational motion is when a body, such as the planet Earth, rotates on its own axis, which remains stationary. While the movement of translation refers to the movement that the Earth makes when rotating in its orbit around the Sun.

The rotational movement of the Earth lasts 24 hours, and the translational movement lasts one year.

Rotation of the Earth Translation of the Earth

Definition Return of the Earth on its own axis. Return of the Earth around the Sun.
Duration 24 hours. 365 days and 6 hours approximately.
Impact The day and the night. The seasons of the year.
Speed 1,700 kilometers per hour at the equator. 108,000 kilometers per hour.

What is rotational movement

The rotation that the planet Earth gives on its own axis due to the action of gravity is called rotational movement.

This movement in which the Earth rotates lasts 24 hours, which allows time to be measured throughout the day. As the planet Earth rotates, it exposes one part to the Sun and the other remains in the shadow, this is how day and night occur in different parts of the world.

As a consequence, the various areas of the planet have different schedules. For example, when in Mexico it is 2:00 pm, in Russia it is 10:00 pm. The city of Gisborne in New Zealand is the first to be illuminated by the sun’s rays.

The rotational movement goes from west to east, counterclockwise, which is why the sun rises in the east and sets in the west. Thanks to this we can locate the cardinal points, just as it can be determined taking into account the location of the Moon at night.

In addition, the rotation movement allows the winds and sea currents to move in the opposite direction in each hemisphere, producing a phenomenon known as the Coriolis effect.

Due to the speed and constant spin of the planet during rotation, the shape of the Earth is not completely round. Rather, the poles are flattened and the center widened.

What is translational motion

Translational movement occurs when the planet Earth rotates in its orbit around the Sun due to the action of gravity.

This movement, from when the Earth begins to return to the Sun until it reaches the point where it began, lasts approximately 365 days and 6 hours.

The additional 6 hours accumulate until they become 24 hours after 4 years. For this reason, every 4 years there is a year with 366 days known as a leap year, February 29 is the extra day.

Just as the rotation movement allows the hours of the day to be measured, with the translation movement the days of the year can be counted.

As the axis of the Earth is tilted, the translational movement occurs at an approximate angle of 23.5º with respect to the elliptical.

The path of the Earth around the Sun is slightly elliptical and the average speed of displacement on the plane of the elliptical is 108,000 kilometers per hour.

The furthest point that the Earth gets to be from the Sun during the movement of translation is 152,098,232 kilometers away. This distance occurs in the month of July and is known as aphelion.

On the other hand, the closest point of the Earth to the Sun is 147,098,290 kilometers away during the month of January and is known as perihelion.

Seasons of the year

The seasons of the year depend directly on the position of the planet in the orbit during the movement of translation. These begin on different dates of the year and are known as solstices and equinoxes.

  • Winter Solstice (Northern Hemisphere: December 21; Southern Hemisphere: June 21).
  • Spring equinox (northern hemisphere: March 21; southern hemisphere: September 21).
  • Summer solstice (northern hemisphere: June 21; southern hemisphere: December 21).
  • Autumn equinox (northern hemisphere: September 23; southern hemisphere: March 21).
  • During the movement of translation, the speed with which the Earth moves varies: when it is closer to the Sun the speed increases and when it moves away it slows down. As a consequence, the seasons have different durations and do not always start on the same date.

    In addition, the tilt of the Earth causes the sun’s rays to arrive with different intensity in each hemisphere of the planet, causing some areas to receive more solar radiation than others.

    Thus, summer, autumn, spring and winter can experience changes depending on how close each hemisphere is to the sun.

    For example, when the southern hemisphere is close to the Sun it is summer, then in the north it is winter, because the northern hemisphere will be farther from the Sun.

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    Theories about translational and rotational movements

    Formerly, it was believed that the Sun, the stars and the heavenly bodies revolved around the Earth, located in the center of the galaxy. This theory is known as geocentrism.

    The astronomer Nicolaus Copernicus (1473-1543) dedicated himself to the task of studying something totally opposite, the heliocentric theory. According to this theory, the planet Earth is the one that revolves around the Sun.

    The heliocentric theory was published in Copernicus’s book entitled On the turns of the celestial orbs in the year 1543, displacing the geocentric hypothesis.

    Copernicus observed the movement in the position of the stars in the sky and thus concluded the rotation of the Earth. This theory was later confirmed by Galileo Galilei (1564-1642).

    Based on the heliocentric theory, the Earth is in constant motion along with the rest of the planets and bodies in the solar system. The two types of movement it makes are rotation and translation, which, although imperceptible to humans, have a significant impact on everyday life.

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