Our planet, Earth, is in constant motion and belongs to the solar system. Over time, we have learned that these movements are crucial for life on Earth and affect various aspects of our environment, such as the succession of day and night, the seasons, and even the weather. There are several types of movements of the earth, the most important of which are rotation, translation, precession and nutation. These four movements are key to understanding the behavior of our planet and its interactions with the Sun and other celestial bodies.
In this article we are going to delve into the main movements of the Earth, understanding each of them, their characteristics and the relevance they have in daily life.
Earth movements
The movements of the Earth They can be classified into two large groups: the best-known movements, such as rotation and translation, and more complex movements such as precession and nutation. These movements explain everyday phenomena such as the seasons of the year, but also others that are more difficult to perceive with the naked eye, such as changes in the orientation of the Earth's axis.
Rotation
The rotation movement is undoubtedly one of the best known. The Earth rotates on its own axis from west to east in a counterclockwise direction. This complete turn takes 23 hours, 56 minutes and 4 seconds, which gives rise to what we know as a sidereal day.
This rotational movement is responsible for the alternation of days and nights, since as the Earth rotates, it exposes different parts of its surface to the Sun, illuminating some and leaving others in darkness. It is easy to observe this on a daily basis, since when it dawns in one part of the world, it is night in another.
Another interesting aspect of this movement is that not all points on Earth rotate at the same speed. At the equator, the speed of rotation is approximately 1600 km/h, while at more northern or southern latitudes, this speed decreases. For example, at 45º north latitude, the speed is about 1073 km/h.
Another crucial effect of the rotational movement is the formation and maintenance of the terrestrial magnetic field, which protects our planet from the solar wind. This magnetic field is key to life, as it protects us from space radiation and allows the development of the atmosphere as we know it.
Translation
The translational movement is the displacement of the Earth around the Sun, in an elliptical orbit. The Earth takes exactly 365 days, 5 hours, 48 minutes and 45 seconds in completing a full revolution around the Sun, which we know as a solar year. Because this time is not exactly 365 days, what we call leap-year every four years, in which an additional day is added in February to adjust for this gap.
It is a common misconception that it is warmer in summer because the Earth is closer to the Sun. In fact, in the northern hemisphere, the Earth is farther from the Sun in summer than in winter. The cause of the seasons is the tilt of the earth's axis, which is 23,43 degrees. In summer, the sun's rays hit the place where we live more directly, causing temperatures to rise, while in winter the sun's rays hit more obliquely, causing colder temperatures.
The Earth travels a distance of 938 million kilometers in its orbit around the Sun, moving at a speed of about 107.280 km/h. Despite this impressively high speed, we do not feel it due to the force of gravity that keeps us anchored to the surface of the planet. It is this translation that also causes the solstices (summer and winter) and the equinoxes (spring and autumn), key moments in the cycle of the seasons.
Aphelion and perihelion
Aphelion refers to the point at which the Earth is farthest from the Sun, and occurs in the month of July, while perihelion is the point of closest proximity to the Sun, which occurs in January. During aphelion, the average distance from the Earth to the Sun is 152,6 million km, while at perihelion it is approximately 147,5 million km.
The fact that these events occur at different seasons in the Northern and Southern Hemispheres has to do with the Earth's tilt. While it is winter in the Northern Hemisphere during perihelion, it is summer in the Southern Hemisphere, and during aphelion, the seasons are reversed.
Other movements of the Earth
In addition to the well-known rotation and translation movements, the Earth experiences other complex movements, such as precession and nutation.
Precession motion
The precession of the equinoxes is a very slow movement that affects the orientation of the Earth's axis of rotation. This phenomenon is caused by the gravitational pull exerted by the Sun and the Moon on the Earth's equatorial bulge. Currently, the inclination of the Earth's axis is 23,43 degrees, but this inclination varies very slowly over thousands of years.
The complete precession cycle lasts approximately 25.700 years and is responsible for the slow change of the seasons over millennia. This movement, although imperceptible to humans, is of great importance at a geological and climatic level.
Nutation movement
The nutation movement is a slight oscillation of the Earth's axis of rotation that occurs due to the gravitational influence of the Moon and the Sun. This oscillation has a cycle of 18,6 years and is caused by the Earth's equatorial bulge. Although this motion is less well known, it has a subtle influence on the climate and the accuracy with which celestial positions are measured from Earth.
An example similar to nutation is the motion of a spinning top when it is about to stop, oscillating up and down. Although it is not perceptible to the naked eye, it is an astronomical phenomenon of great interest.
Other related phenomena: Chandler's wobble
Another movement related to those mentioned is the so-called Chandler's WobbleThis phenomenon describes an oscillation of the Earth's axis of rotation and has a cycle of 433 daysIt adds a small adjustment of 0,7 arcseconds to the precession of the equinoxes and, although subtle, is the subject of study within astronomy.
This movement was discovered by astronomer Seth Carlo Chandler in 1891 and, although its origin is not entirely clear, it is believed to be related to fluctuations in the distribution of the Earth's mass, geophysical movements beneath the crust and even changes in the atmosphere and oceans.
The constant movement of the Earth not only affects the length of days and seasons, but also plays a crucial role in climate cycles, and some of these movements are only perceptible through precise astronomical measurements.