Once a month, The duty launches to history buffs the challenge to decipher a current topic from a comparison with a historical event or person.
Over the past decade, the Kepler Space Observatory has been used to examine more than half a million stars for Earth-like exoplanets. The name of this exploration platform honors the German astronomer Johannes Kepler (1571-1630), whose 450 will be celebratede birthday on December 27.
Eclipsed by Nicolas Copernicus and Galileo Galilei, Kepler is sometimes perceived as a secondary actor whose work was used by Isaac Newton in the development of the theory of universal gravitation. However, Kepler deserves to be in the pantheon of giants who transformed our vision of the universe and established the foundations of contemporary science.
Kepler was born in Württemberg, Germany, in 1571. At the age of three he suffered from smallpox; he got away with deformed hands, weakened eyes, and a health that will always remain vacillating. He entered the University of Tübingen in 1587, where he studied with the astronomer and mathematician – himself well known – Michael Maestlin (1550-1631). The latter, convinced of the fundamental veracity of the heliocentric system of Copernicus, initiated Kepler, whose ambition was to become a Lutheran minister.
In 1594, wanting to get rid of a potential free-thinker cleric, the masters of the University of Tübingen recommended Kepler to fill the post of professor of mathematics in Graz, Austria. The latter accepts by reluctantly abandoning his theological studies.
It was there that in 1595, during a mathematics class where he circumscribed a triangle in a circle, he had an idea that he considered extraordinary: “There are six planets because there are five perfect solids. : a perfect solid inserted exactly between two planets. »He explored this idea further, made his calculations and published everything in 1596 in Celestial Mechanics (Mysterium Cosmographicum). Very pious, he was indeed convinced to have pierced “the secret of the world”. Kepler sent copies to Galileo and Tycho Brahe, then Imperial mathematician. Although the latter does not agree on several points, he is very impressed by the talents of the young author and invites him to come to his home in Prague.
Kepler witnessed Tycho’s last hours. The latter died suddenly in 1601 at the age of 54 following a blockage of urinary functions during a banquet offered by the imperial councilor Minckwicz. Two days later, Emperor Rudolf II of Hungary appointed Kepler Imperial Mathematician.
Illuminated
Kepler was a contemporary of Galileo (1564-1642), with whom he exchanged books and correspondence, but their relationship remained difficult, the Italian astronomer showing little openness towards his young colleague, whom he perceived as “enlightened”. If Kepler is not recognized in the popular imagination like his contemporary Galileo, his contributions to celestial mechanics and optical principles are even more fundamental than those of the flamboyant Italian scientist.
Shortly before his death, Brahe had entrusted Kepler with the task of calculating the orbit of Mars from the observations he had made and had jealously kept for himself until then. Kepler believed that a few weeks would be enough for him. Apart from that of the Moon, the orbit of Mars is the most elliptical of orbits known at the time; it took him more than six years of labor to come up with his first two laws of planetary motion, and almost ten years to establish the third.
Kepler’s most memorable and living legacy is his set of the Three Laws of Planetary Motion. Kepler proposed the first two laws in 1608, and the third in 1619. Historians remind us that Kepler’s texts are difficult. Perhaps this opacity of Kepler’s writings is one of the reasons for Galileo’s stubborn refusal of the elliptical shapes of planetary orbits and non-uniform motion proposed by Kepler.
The latter rid the Copernicus system of eccentric orbs having a different center for each planet; he eliminated the epicycles that the Polish astronomer had to keep to account for the variation of the brightness and the speed of the planets in their course of the celestial vault!
Astronautics today offers a fireworks display of applications and uses of Kepler’s laws. Starting with interplanetary missions like To travel1 and Traveling 2 to the giant planets, New horizons which grazed Pluto to then reach the transneptunian object Arrokoth, Rosetta which joined and accompanied comet Churyomov-Gerasimenko, as well as all space missions to the Sun, Moon, Mercury and Venus.
All these machines take trajectories described by Kepler’s laws. It is fitting that the exoplanet exploration and research platform launched by NASA in 2009 has been named Kepler. To date, more than 2,500 exoplanets on the mission Kepler were confirmed by subsequent observations on the ground or in space.
The mission ended on October 30, 2018, but data analysis continues and will reveal hundreds of more exoplanets. On the ground, large infrared telescopes followed the movements of the stars in the center of the Milky Way. These observations made it possible to derive their orbital parameters; the stars follow elliptical trajectories, obeying Kepler’s laws. We were thus able to infer the mass of a super massive central object, a black hole 4.1 million times the mass of the Sun.
Tolerance
Kepler’s work becomes even more valuable when we know under what miserable conditions it was performed. The German astronomer lived and worked in the heart of Central Europe torn apart by the Reformation and the Counter-Reformation when Catholics, Lutherans, Calvinists and Utraquists clashed violently.
Harassed by his creditors, and in constant expectation of his fees promised by various trustworthy guardians, Kepler was continually short of money. Contemporary and victim of great heresies, he often had to flee from the excesses of religious fanaticism.
Kepler synthesized his thinking about the heliocentric system in Epitome Astronomiae Copernicana published in three volumes (1617, 1620 and 1621), which he wrote in parallel with The harmony of the world (1619), thus provoking the Holy Office which put all of its work on the Index.
A staunch Lutheran, Kepler preached tolerance: for that, he was accused of being doubly heretical, first by deviating from the official belief, then by demanding that we accept communities of other beliefs. His family life brought him little happiness, marred by the illness of his children as well as the mourning of his first wife and four of his children.
In addition, Kepler had to face the oppression of the witch hunt. In August 1620, his mother Katrina Kepler (1546-1622) was arrested and accused of witchcraft. Among the 49 charges, each as eccentric as the next, it was claimed that she would have caused “indescribable pain” to neighbors by her medicinal potions and “caused the death of a calf two years old after having her. touch “. Threatened with torture, she refused to confess anything. Kepler hires lawyers and organizes the defense. In a 128-page document he largely wrote, the astronomer demolishes the prosecution’s arguments. After six years of legal twists and turns, as cruel as it is absurd, the court frees Katrina, not without showing the accused the instruments of torture and a detailed description of their use, a procedure called territory verbalis (threats of torture).
In the fall of 1630, Kepler left the town of Sagan in present-day Poland for Regensburg (Regensburg), where he died on November 15, 1630 after a brief illness, at the age of 58. Due to the Thirty Years’ War, all traces of its monument and its remains have been lost. His manuscripts, recovered under the guidance of mathematician Leonhard Euler by Catherine the Great, Empress of Russia from 1762 to 1796, are in the Pulkovo Observatory in St. Petersburg, Russia.
Kepler’s legacy is part of the chaotic evolution of our understanding of the cosmos. The astonishing advances that Kepler has made in our understanding of the mechanics of the stars make him a giant in the history of astronomy. Despite all kinds of obstacles, illnesses, bereavements, wars and persecutions, Johannes Kepler is a beacon illuminating the darkness of sectarianism.
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