### Education, The science

# Who discovered the laws of planetary motion?

"Kepler's Laws" - this phrase is familiar to everyone who is fond of astronomy. Who is this person? The relationship and interdependence of what objective reality he described? The astronomer, mathematician, theologian, philosopher, cleverest man of his time, Johannes Kepler (1571-1630) discovered the laws of motion of the planets of the solar system.

## The beginning of the way

Johannes Kepler, a native of Weil der Stadt (Germany), came to this world in December 1571. A weak, poor-sighted child has overcome everything in order to win in this life. The boy's studies began in Leonberg, where the family moved. Later he moved to an institution of an elevated type - a Latin school to learn the basics of the language that he intended to use in future publications.

In 1589 he graduated from the school at the monastery of Maulbronn in the town of Adelburg. In 1591 he entered the University in Tübingen. An effective educational system was created by the Dukes in the wake of the introduction of Lutheranism. With the help of grants and scholarships for the poor, the authorities tried to provide universities with applicants, from which it was possible to bring up well-educated clergymen, capable of defending a new faith in times of raging religious disputes.

During his stay at the educational institution Kepler fell under the influence of Professor of Astronomy Michael Meestlin. The latter secretly shared Copernicus's views on the idea of the heliocentric (Sun in the center) universe, although he taught the students "according to Ptolemy" (Earth in the center). A profound knowledge of the ideas of the Polish scientist aroused Kepler's great interest in astronomy. So the theory of Copernicus had another supporter, striving to personally comprehend the laws of planetary motion around the Sun.

## The solar system is a work of art

Ironically, the one who subsequently discovered the laws of planetary motion did not consider himself an astronomer by vocation. Throughout his life Kepler believed that the solar system - a work of art, full of mystical phenomena, dreamed of becoming a priest. His interest in Copernicus' theory was explained by the astronomer by the fact that he must study different opinions before drawing conclusions from his own research.

Nevertheless, university professors spoke of Kepler as a student with an excellent mind. In 1591, after receiving a master's degree, the scientist continued his studies in the field of theology. When they were close to completion, it became known that a professor of mathematics died in the Lutheran school in Graz. Tubingen University recommended taking on this position a talented in all respects a graduate. So, forgive the laws of planetary motion?

## In the name of God

The 22-year-old Johann reluctantly abandoned his original vocation to be a priest, but nevertheless took up the duties of a mathematics teacher in Graz. During the lectures in his class, the beginning teacher pictured on the board some geometric figures with the participation of concentric circles and triangles. And suddenly he was puzzled by the idea that such figures reflect a certain fixed ratio between the sizes of two circles, provided that the triangle is equilateral. And what is the ratio of the sizes on the area between the two circles? The thought process was gaining momentum.

A year later, an unusual theologian published his first work "The Mystery of the Universe" (1596). In it he expounded his creative views on the secrets of the universe, backed by religious beliefs.

He who discovered the laws of planetary motion did so in the name of God. Expanding the mathematical plan of the universe, the researcher came to the conclusion: six planets are enclosed in spheres, between which five regular polyhedra fit. Of course, the version was based on the "fact" that there are only 6 celestial bodies. Around the Earth's orbit, Kepler outlined an ideal dodecahedron and a sphere touching the orbit of Mars.

## Perfect polyhedra

Around the area of Mars, the scientist depicted a tetrahedron and a sphere adjacent to the orbit of Jupiter. In the icosahedron in the orbital sphere of the Earth the sphere of Venus has perfectly "blended". Using the remaining types of perfect polyhedra, this was done with the rest. Strikingly, the ratios of the neighboring planetary orbits presented in the nested model of the Kepler spheres coincided with the calculations of Copernicus.

Discovering the laws of planetary motion, the priest with the mathematical mind relied primarily on divine inspiration. He had no real basis for arguments. The meaning of the treatise "Secrets of the Universe" is that this was the first decisive step towards the recognition of the heliocentric system of the world, as set out by Copernicus.

## Assumptions against high accuracy

In September 1598, Protestants in Graz, including Kepler, were forced out of the city by Catholic rulers. Although Johann was allowed to return, the situation remained very tense. In search of support, he turned to Tycho Brahe - mathematics and astronomer at the court of Emperor Rudolph II. The scientist was known for his impressive collection of planetary observations.

He knew about the work "The Mystery of the Universe". But when in 1600 his creator arrived at the Quiet Observatory located outside the city of Prague, Braga, engaged in high-precision (at that time) research, welcomed him as the author of a particular work, but not as his colleague. Confrontation between them continued until the death of the Danish astrologer, which occurred in a year. After the opponent left the world, Kepler was trusted to guard the treasury of his observations. They greatly helped the researcher to become the one who discovered the laws of planetary motion around the Sun.

## The Path of Mars

Recent studies by Braga on the creation of a table of planetary motion have not been completed. All hopes were placed on the successor. He was appointed an imperial mathematician. Despite tense relations with his late colleague, Kepler was free to pursue his own interests in astronomy. He decided to continue his observations of Mars and describe his own vision of the orbit of this planet.

Johann was sure: having discovered the difficult Martian way, one can reveal the ways of movement of all the other "Wanderers of the Universe". Contrary to popular belief, he did not just use Braga's observations to select a geometric figure that corresponds to the description. Yesterday's theologian sent efforts to the discovery of the physical theory of the movement of "sisters who live in an airless space," from which their orbits can be deduced. After the titanic research work, three laws of planetary motion appeared.

## The First Law

*I. The orbits of the planets are ellipses with the Sun in one of the foci.*

The law of motion of planets in the solar system has established that the planets move in an ellipse. He appeared after eight years of calculations using a database compiled by Tycho Brahe based on observations of the planetary motion of the Star of Mars. Johann called his work "New Astronomy".

So, according to Kepler's first Law, any ellipse has two geometric points called foci (singular focus). The total distance from the planet to each of the foci is always added together the same regardless of where the planet is in the path of its movement. The importance of the discovery is that the assumption that orbits are not ideal circles (as in geocentric theory) has brought people closer to a more accurate and clearer understanding of the world picture.

## The Second Law

*II.* *The line connecting the planet with the Sun (radius vector) overcomes equal areas at equal intervals of time, while the planet moves around the ellipse.*

That is, in any time interval, for example, in 30 days, the planet overcomes the same area, regardless of what period you choose. It moves faster when approaching the Sun and slower when removed, but it comes with an ever-changing speed when it moves around its orbit. The "smartest" movement is observed at perihelion (the closest point to the Sun) and the most "sedate" movement in aphelion (the point farthest from the Sun). So he reasoned the one who discovered the laws of the motion of the planets.

## The Third Law

*III.* *The square of the total period of orbital revolution (T) is proportional to the cube of the average distance from the planet to the Sun (R).*

This principle is sometimes called the law of harmony. He compares the orbital period of time and the radius of the orbit of the planets. The essence of Kepler's discovery lies in the following: the ratio of the squares of the periods of motion and cubes of average distances from the Sun is the same for each planet.

Again, the laws of motion of Kepler's planets were based on long-term serious observations and mathematically processed. Showing regularities, they did not reveal the conditioning of phenomena. Later, the famous discoverer of the law of universal gravitation Newton proved that the riddle was covered in the physical property of bodies attracted to each other.

## The shadow of my body is here

Despite his success, Kepler constantly suffered from financial troubles, lack of time for research, travel in search of places where he tolerated his religious beliefs. Several times he tried to get a teaching post in Tübingen, but was perceived as a traitor, a Protestant and was refused.

Johannes Kepler died on November 15, 1630, from an attack of acute fever. He was buried in the Protestant cemetery. In the epitaph, his lawful son wrote: "I used heaven to measure. Now I have to measure the shadows of the Earth. Despite the fact that my soul is in heaven, the shadow of my body lies here. "

Yes, initially in the spirit of medieval concepts, the scientist believed that the planets move because they have souls, this is living magic, and not just lumps of matter. Later, he realized that the scientific approach is more justified. Well, the priest and the astronomer, who discovered the laws of planetary motion, honestly went through the path of insight. But we admit to ourselves: sometimes it seems that there are so many mystics in the whole of the scientific universe!

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