Nutation movement

nutation movement of the earth

We know that our planet has several types of movements such as translation and rotation. However, it also has a movement less known by the population and is known by the name of nutation. He nutation movement It is very important and it is necessary to know it to know more about planet Earth.

Therefore, in this article we are going to tell you what the nutation movement is, its characteristics and importance.

What is the movement of nutation

obliquity of the ecliptic

The movement of nutation is a phenomenon that occurs in some rotating objects, such as the Earth. can be compared to the subtle rocking of a top that has already begun to spin. In the case of our planet, nutation is a slight additional movement superimposed on the main rotation.

Imagine that the Earth is a perfectly balanced top spinning around an axis. However, due to the influence of different external forces, such as the Moon and the Sun, the way it rotates is not completely uniform. These unequal forces influence the Earth's axis of rotation, creating an additional rocking effect.

As a result, the Earth undergoes a to-and-fro motion, or nutation, as it rotates around its axis. This movement is characterized by small oscillations that occur over a period of time. Nutation is responsible for the fact that the axis of rotation of the Earth is not fixed in relation to the stars, but rather presents a slight variation over time.

The main cause of this nutation movement is the gravitational influence of the Moon and the Sun on the Earth. These celestial bodies exert an attractive force that generates a rocking effect on the planet's rotation. In addition, other factors such as the uneven distribution of the Earth's mass and variations in its internal structure also contribute to the phenomenon of nutation.

It is important to note that nutation it is a very small movement and difficult to perceive directly. However, its existence is of great importance in fields such as astronomy and geodesy, since it influences the precision of calculations related to the location and orientation of celestial bodies and the measurement of time.

Why does it occur?

precession and nutation

Nutation occurs due to the external gravitational force that exists between the Moon, the Sun and the Earth and the equatorial bulge, which makes our planet not a perfect sphere. Therefore, the reason for nutation is based on the fact that the orbital plane of the Moon revolving around the Earth is inclined about 5 degrees with respect to the orbital plane of the Earth that revolves around the Sun.

The Moon's orbital plane is 18,6 years ahead of Earth's. The Moon's influence on the precession varies during the same period. In addition to the more well-known movements of the Earth, such as rotation and translation, there are other, lesser-known types of movement, such as precession and nutation. This is the Chandler wobble, a small wobble in Earth's rotation, consisting of a 0,7 second arc segment, lasting 433 days until precession.

This movement It was discovered by the American space expert Seth Carlo Chandler in 1891., and its cause is still unknown. Some hypotheses suggest that it arose due to changes in the circulation of air masses due to climate fluctuations, possible geophysical developments under the outer layers of the world, changes in the concentration of salt in the oceans, etc.).

Importance of nutation movement

nutation movement

The nutation movement is of great importance in the field of astronomy due to its influence on the accuracy of astronomical calculations and the precise determination of the location and orientation of celestial bodies. Next, we are going to see some of the reasons why nutation is relevant in this field:

  • Precession of the equinox: Nutation is one of the factors contributing to the precession of the equinox. This precession is a slow change in the position of the equinox and solstice points over very long periods of time. Nutation modifies the speed and direction of this change, which influences the precise determination of celestial coordinates and time.
  • Determination of the proper motion of stars: Nutation motion affects the apparent position of stars in the sky. This implies that astronomers must take this motion into account to calculate and correct for the proper motion of stars, that is, their actual motion through space relative to the solar system.
  • Astronomical coordinates: Celestial coordinates, such as right ascension and declination, are used to locate celestial objects in the sky. Nutation can introduce small variations in these coordinates, requiring fine corrections for more accurate measurements and calculations.
  • determination of time: Nutation also influences the measurement of time in astronomy. Astronomical phenomena, such as eclipses and planetary ephemeris, are used to establish time references. Nutation affects the apparent position of these events, requiring adjustments to accurately determine the dates and times at which they occur.

Precession motion

precession

The Earth is not a perfect sphere, but an irregularly shaped spheroid, crushed at the poles and deformed by the gravitational pull of the Sun, the Moon and, to a lesser extent, the planets. This causes a very slow wobble of the planet during its translational movement, called precession, in the opposite direction of its rotation, that is, retrograde (clockwise).

Under the influence of these attractive forces, the axis describes a double cone with an opening of 47°, whose vertex is at the center of the Earth. The position of the celestial poles has changed over the centuries due to the precession of the equinoxes. Currently Polaris does not exactly coincide with the North Celestial Pole. Other planets in the solar system also exhibit this behavior.

I hope that with this information you can learn more about nutation movement and its characteristics.


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