Despite the fact that many of us study in elementary school only the two "main" movements of the earth: rotatory motion y translation movement, the truth is that this topic expands a little further, since the earth does not rotate on itself at a completely right angle because it is slightly tilted on its axis by a few degrees.
Do you know what the movements of the Earth are besides Rotation and Translation?
It is important to take into consideration that, in addition to the 2 best-known movements that I have already mentioned in the previous paragraph, the earth makes 3 other movements: Precession of the equinoxes, nutation movement and chandler wobble, that explain some natural phenomena and the length of days and nights throughout the year, for example.
These additional considerations were raised progressively after the acceptance that our planet is, in fact, spherical and that we live in a heliocentric and not a geocentric system, as was believed a little over 500 years ago.
Therefore, to fully decipher the mechanics that govern our planet, it is essential to know and understand very well what are the movements of the earth and its consequences for terrestrial life.
Our planet Earth is really fascinating and worth studying in depth, but did you know that NASA has discovered other planets similar to ours in the cosmos? Don't miss our article on Earth-like planets.
Before going deeper into the matter of the consequences of the movements of the Earth, it will be better to review the most basic principles such as the movements of rotation and translation of the Earth.
Rotatory motion
The rotational movement of the Earth is probably the best known and studied of the movements of the earth by the general public. This movement corresponds to the turn that the planet makes on its own axis and that takes 24 hours to complete a full revolution, if a point on its surface is taken in reference to the sun. This is known as sun day.
At what speed does the Earth rotate on itself?
The speed with which our planet rotates around its own axis has been calculated:a is 1670 km/h, if measured just above the equator, where it is greatest. The speed decreases as it advances towards the terrestrial poles and the sphere shrinks.
It's amazing to think that our planet rotates at such a high speed and we can barely even notice it. This phenomenon would perfectly explain one of the principles of Einstein's relativity law, in which the perception of movement depends on the speed at which the observer moves. As we move on the Earth at the same speed, we are not aware of the rotation, but an astronaut on the International Space Station can perfectly notice it.
The Earth's rotation movement is carried out in a West-East direction, which means that if we could see our planet from above (north pole) in space, it would rotate in a counterclockwise direction, just like almost all the others. planets of our solar system, with the exception of Venus.
Consequences of the terrestrial rotation movement
That the Earth does not stop spinning on itself produces certain consequences on the atmosphere that, in fact, are very important for the support of life as we know it. If the Earth suddenly stopped spinning, life could not exist!
What are the effects of Earth's rotation?
The day and the night.
Without a doubt this is the most important and notorious of all the effects of rotation on the movements of the Earth. Day and night occur because the Earth, as it rotates, changes position with reference to the sun in a cyclical manner (every 24 hours).
This phenomenon, which we know as “days”, allows the planet to be safely exposed to solar radiation in parts. Absorbing heat during the day and discharging it at night, which helps regulate the cycles of all living things on the planet.
Bulge in Ecuador
The shape of the planets, bulging in the center (Equatorial Line) and flattened towards the poles, is due to the deformation produced by the effect of the centrifugal force generated as a result of the planet's perennial rotation. This effect is important in natural phenomena such as ocean tides.
Winds
The winds that we feel in the atmosphere of our planet are produced as a consequence of its own rotation, since this produces an inertial movement, causing the gases contained in the interior to rotate proportionally but in the opposite direction in reference to the direction of rotation.
Translation movement
Translation is one of the 2 main movements of the earth, in this case the planet revolves around the solar orbit due to the effect of the gravity exerted by the Sun. A translation turn in the solar orbit lasts 365 days, 5 hours and 47 minutes, which corresponds to what we know as a calendar year. Due to the powerful effect of the solar force of gravity on our planet, the Earth moves along its orbit at an amazing speed of 106.200 km/h.
Our planet is at an average distance of 150 million kilometers from the sun, but this can vary slightly depending on the position of the planet in the orbit, which does not draw a perfect circle, but rather an elliptical shape. The Earth is closest to the sun during the month of January, which produces for us the effect known as perihelion (the closest point of distance to the sun during orbit).
Consequences of translational motion
The main effect of translational movement on life on our planet is the succession of climatic seasons throughout the year.
Although in the area near the Equatorial Line (terrestrial tropics), these changes are not very noticeable, as we move towards the terrestrial poles, the climatic changes throughout the year become more marked.
This occurs due to the tilt of the Earth on its axis as it revolves around the sun, which means that, for long periods of time each year, the sun's rays are less inclined (winter) or completely direct (summer) .
Earth movements: precession of the equinoxes
With the precession of the equinoxes we go a little deeper into the matter and the subject becomes more complex. Let's see, the Earth not only rotates on its axis in a horizontal orientation (rotation) and around the sun (translation), it also rotates on itself like a top does, changing the direction of its poles in reference to space.
In this case, it is a slow and gradual transition that causes the earth's axes to move in a circular fashion around the ecliptic pole. This movement takes a total of 25.776 years to complete one turn of its orbit.
Each cycle of 25.776 years completed in this movement is known as a platonic year and it takes so long because the rotation of the polar tilt around the ecliptic pole is very slow. The tilt moves at about 50.3 sexagecimal seconds per year, moving the earth one degree every 71 years.
To better understand this movement, we could imagine a spinning top. The top not only turns on itself, it also wobbles from one side to the other, causing its tip (or pole) to change position with respect to space from time to time.
As we have mentioned, it is a very slow movement and could explain the periods of drastic climatic changes on the planet, such as the well-known ice ages.
Nutation movement
Nutation is another of the movements of the earth, which complements and makes more complex the movement of the earth's tilt in relation to the ecliptic pole.
In this sense, the terrestrial axis not only moves describing a circumference around the imaginary pole (equinoctial transition), it also wobbles from one side to the other, periodically oscillating the inclination of the earth from left to right due to the effect of the same weight of the planet when affected by the gravitational forces of the Sun and the Moon simultaneously.
This movement is also very subtle, although not as subtle as the equinoctial transition. The terrestrial nutation it causes the planet to “wobble”, oscillating about 9 seconds of arc in reference to its own axis every 18 years.
This movement was discovered by the astronomer James Bradley when studying the orientation of the terrestrial polar axes in reference to the point of Aries.
Chandler Wobble
Chandler's wobble is, of the earth movements, the one that has been discovered more recently, just over 100 years ago, in 1891.
The Chandler wobble is a subtle variation in the axis on which the earth spins, currently varying at a rate of just 0.7 arcseconds every year and a half.
The causes that produce the Chandler wobble on the Earth's axis are unknown, but at the moment it is believed that it occurs due to the redistribution of the Earth's mass as it rotates, mainly the ocean floors. However, this theory is not yet proven.