Rotational motion is when a body, such as the planet Earth, rotates on its own axis, which remains fixed. While translational movement refers to the movement that the Earth makes in the rotate in its orbit around the Sun.
The rotation of the Earth lasts 24 hours and the translational movement lasts a year.
| Rotation of the Earth | Translation of the Earth | |
|---|---|---|
| definition | Earth’s rotation on its own axis. | Revolution of the Earth around the Sun. |
| duration | 24 Hours. | 365 days and 6 hours approximately. |
| Consequences | 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 motion?
The rotation of the planet Earth on its own axis by the action of gravity is called rotational motion.
This movement in which the Earth rotates has a duration of 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 shade, this is how day and night pass in different parts of the world.
As a consequence, the various areas of the planet have different schedules. For example, when it is 2:00 pm in Mexico, it is 10:00 pm in Russia. The city of Gisborne in New Zealand is the first to be illuminated by the sun’s rays.
The rotational motion is from west to east, counter-clockwise, 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 by taking into account the position of the Moon at night.
In addition, the rotational movement allows winds and ocean currents to move in opposite directions in each hemisphere, producing a phenomenon known as Coriolis effect.
Because of the rapid and constant spinning of the planet during the rotational motion, the shape of the Earth is not completely round. Rather, the poles are flattened and the center widened.
What is translational motion
The translational movement occurs when the planet Earth rotates in its orbit around the Sun by the action of gravity.
This movement, from the time the Earth begins its return to the Sun until it reaches the point where it started, has a duration of 365 days and 6 hours about.
The extra 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 being the extra day.
Just as the rotational movement allows you to measure the hours of the day, with the translational movement you can count the days of the year.
Since the Earth’s axis is tilted, the translational movement occurs at an approximate angle of 23.5º with respect to the elliptical.
The trajectory 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 farthest point that the Earth reaches from the Sun during translational movement is 152,098,232 kilometers away. This distance is presented in the month of July and is known as affiliation.
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
The seasons of the year depend directly on the position of the planet in the orbit during the translational motion. These start 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).
- Autumnal Equinox (Northern Hemisphere: September 23; Southern Hemisphere: March 21).
During the translational movement, the speed with which the Earth moves varies: when it is closer to the Sun the speed increases and when it is further away the speed decreases. As a result, 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 reach each hemisphere of the planet with different intensity, causing some areas to receive more solar radiation than others.
Thus, summer, autumn, spring and winter can experience changes depending on the proximity of each hemisphere 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 further away from the Sun.
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Theories about translational and rotational movements
In ancient times, it was believed that the Sun, the stars and the stars revolved around the Earth, located at the center of the galaxy. This theory is known as geocentrism.
the astronomer Nicolaus Copernicus (1473-1543) devoted himself to the task of studying something completely 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’ book entitled On the turns of the celestial orbs in 1543, displacing the hypothesis of geocentrism.
Copernicus observed the movement in the position of the stars in the sky and thus came to the conclusion of 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 of the solar system. The two types of movement it makes are rotation and translation, which, although imperceptible to human beings, have an important impact on everyday life.