The Motions of the moon and the earth Are physical and natural phenomena that occur with a certain regularity and with direct consequences on the life of the inhabitants of this planet.
The Earth is the third planet in the solar system if its location with respect to the sun is taken into account, but it is the fifth if its size is considered in relation to the rest of the planets of the system.
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It is located about 149 million kilometers from the sun and travels constantly around it.
The orbit it describes in that movement is not a circle exactly so it is sometimes closer to the sun and sometimes a little further.
The shape of the Earth is that of an irregular sphere whose equator is thickened in 21 kilometers. Its north pole dilates 10 meters and its south pole sinks 31 meters, approximately.
The Earth's atmosphere is rich in oxygen, has many bodies of water and a chemical composition that make life on the surface.
The Moon, on the other hand, is a satellite of the Earth, that is, that revolves around it. This movement affects the level and the tide of the seas. Its distance from the Earth reaches 384 thousand kilometers.
Land movements from a historical perspective
Aristotle Was responsible for a geocentric vision that prevailed for 1000 years. The studies from physics were made attending to this vision in which the Earth was a stationary star with the planets and the sun revolving around it.
Christian theology also contributed to the spread and rootedness of this idea, until a Polish priest named Nicolaus Copernicus, In 1543, he divulged a different one: all the planets, including the Earth, revolve around the sun.
Although his first followers were accused of heretics, among them Giordano Bruno (who was burned at the stake), the scientific evidence that could accumulate with the time and thanks to the works of Galileo Galilei , Johannes Kepler and Isaac Newton , He ended up agreeing.
In fact, Kepler's mathematical equations even today allow us to predict the motion of the planets, and their laws allowed Newton to describe the force that makes these movements possible: gravity.
Much more contemporary are the discoveries related to the influence of these movements on human biorhythms, for example.
What are the movements of the Earth?
1- The translation movement
It is the name that receives, precisely, the movement that makes the Earth around the Sun. In the translation, the earth takes 365 days, 5 hours and 57 minutes. That is, one year. The speed of the planet in this route is 29.5 kilometers per second.
Due to an eccentric movement, the distance between the Earth and the Sun varies in the year: at the beginning of January (perihelion), it is approximately 142,700,000 kilometers; While at the beginning of July, that distance is 151,800,000 kilometers.
2- The rotation movement
This is the movement that makes the earth on its own axis in a West-East direction, for 23 hours and 56 minutes (one day).
It is thanks to this movement that you experience sunlight in the day and darkness in the night.
This was also the movement that humanity took centuries to discover after the Aristotelian theory that the earth was and center of universe.
Precession
It refers to the movement made by the Earth's north pole with respect to the midpoint of the ellipse described by the Earth in its travel around the sun.
Its duration is approximately 25,780 years (the so-called Platonic year), although that number may vary because it depends on the movements of the tectonic plates and the force exerted by the sun on the earth.
This movement occurs in the opposite direction of rotation, ie it is produced clockwise.
4- Nutation
It could be described as the oscillation that occurs during the precession movement, where the circles described are not exact.
This movement occurs by lunar gravity and was discovered in 1728 by James Bradly.
In a single movement there are more than 1,300"loops"of nutation.
5- Chandler Wade
It owes its name to the scientist who discovered it in 1891, Seth Carlo Chandler.
It is an oscillation of the axis of the Earth that can reach up to 9 meters of difference with respect to the predicted position for a certain moment.
Its causes are still unknown.
What are the movements of the Moon?
1- Rotation
The moon, like the earth, revolves around its own axis. This takes little more than 27 days (known as sidereal month).
2- Translating
It is the movement that makes the moon around the Earth, in a West-East direction (although from the earth it is seen in the opposite direction due to the rotation of the planet).
This movement lasts the same as that of lunar rotation, which is why you always see the same face of the moon from the earth.
It is also thanks to this revolution that the Moon advances approximately 12 degrees per day in the sky.
Its center of rotation with respect to the Earth is not parallel to the terrestrial axis, due to the gravitational attraction of the Moon on Earth.
The Moon-Earth orbit (5 ° and 5 ° 18 ') with respect to the plane of the Earth-Sun orbit, is inclined. For this reason only solar or lunar eclipses can be produced at two points in their path, called nodes.
3- Apsidal Precession
It is the movement of the lunar orbit that occurs once every 8.85 years.
References
- Bolte, Mike & others (2000). Motions.
- Johnson, J. P. (s / f). The movements of the moon. Popular Astronomy Review, Vol. 24, p.276. Provided by NASA Astrophysics Data System (ADS).
- Michaelson, Alane (2017). Movements of the Sun, Moon & Earth. Retrieved from: sciencing.com.
- Naukas (2010). The five movements of the earth. Recovered from: naukas.com.
- Penn State Department of Geosciences (s / f). Motions of the Earth. Retrieved from: astro.psu.edu.
- Riebeek, Holli (2009). Planetary Motion: The History of an Idea That Launched the Scientific Revolution. Retrieved from: earthonasa.gov.
- Taylor R. Nola (2014). Does the Moon Rotate? Retrieved from: space.com.