The premise for every thing we understand concerning the orbits of the planets comes from the work of German astronomer Johannes Kepler
Kepler, without knowing concerning the force of gravity, mathematically described the motions of the planets across the sun in his three laws of planetary motion. His work was key in providing evidence for Nicolaus Copernicus‘ theory that the sun, not Earth, was at the middle of the solar system.
When was Kepler born?
Johannes Kepler was born on Dec. 27, 1571, within the Free Imperial City of Weil der Stadt, which today is near Stuttgart, Germany. He was abandoned by his soldier father at a young age and was raised as a Lutheran by his mother and grandparents.
Though neglected as a baby, he displayed a knack for mathematics and witnessed two astronomical events that spurred his interest within the cosmos: the Great Comet of 1577 and a complete lunar eclipse in 1580. Nevertheless, a bout of smallpox left Kepler with crippled hands and damaged eyesight.
As a youngster, Kepler studied at a Cistercian monastery in Adelberg, where he learned Latin, the language utilized by the students of the day, thus setting him up for his academic studies as an adult. He progressed on to the University of Tübingen in Germany, where he studied philosophy.
Kepler, Copernicus and the platonic solids
While at Tübingen, Kepler’s math professor, Michael Maestlin, introduced him to Copernicanism, named after Copernicus, who had died in 1543. This heliocentric, or Sun-centered, model describes how Earth and other planets within the solar system orbit the sun, and never the opposite way around.
Within the late sixteenth century, heliocentrism was still a fringe theory; most individuals believed Earth was at the middle of creation. At Tübingen, Kepler was taught each theories, and upon reading Copernicus’ “De revolutionibus orbium coelestium libri vi” (“Six Books In regards to the Revolutions of the Heavenly Orbs”), he immediately dismissed the geocentric, or Earth-centered, theory in favor of the heliocentric model.
Although heliocentrism made logical sense, observational evidence for the model was missing within the late sixteenth century. Kepler made it his life’s mission to offer that evidence; he saw it as a option to higher grasp God’s grand design. Within the devout times during which Kepler lived, even appeals to logic required divine explanation.
In 1594, Kepler took a post teaching math and astronomy in Graz, Austria, where he had a breakthrough. While twiddling with geometric shapes on a chalkboard, Kepler drew a circle inside an equilateral triangle, with the circle touching the triangle halfway down either side. He then drew one other circle across the triangle, with the circle touching the triangle at each of its three points.
Kepler believed that the ratio of the scale of the circles matched the ratio of the orbits of Jupiter and Saturn, and imagined that between each planet’s orbit was a “platonic solid” — a three-dimensional polyhedron. Kepler interpreted this as a part of God’s underlying geometric design supporting the orbits of the planets. In 1596, he published his ideas in his book “Mysterium Cosmographicum.”
Kepler also worked on another ideas that might be deemed wacky today. For instance, in 1619, he published “Harmonices Mundi,” during which he argued that the motion of the six known planets (before the invention of Uranus and Neptune) could possibly be described by musical tones and that their orbits produced harmonies. Despite these bizarre ideas, Kepler modeled the planets’ orbits more precisely than anyone before him.
Did Kepler kill Tycho Brahe?
In 1600, Kepler traveled to Benatky Castle, near Prague, to work as an observing assistant to Danish astronomers Tycho Brahe and Christen Sørensen Longomontanus. With Longomontanus, Kepler fastidiously tracked the motion of Mars through the sky, mapping its orbit. Kepler noticed that the farther Mars was from the sun, the more slowly the planet moved, and the closer it was to the sun, the faster Mars moved along its orbit.
Those were Kepler’s first steps in providing observational evidence for the heliocentric model. Nevertheless, Kepler was not glad working for Brahe and Longomontanus. For one thing, his superiors were geocentrists and dismissed Kepler’s Copernicanism. Second, Brahe didn’t allow Kepler to access records of his own detailed observations of the heavens made across many years.
Third, the environment at Benatky Castle was raucous, with numerous partying, alcohol and music, and little privacy; Brahe, particularly, was a celebration animal. Kepler issued a set of demands, asking for a more formal contract and higher working conditions, but he was promptly thrown out of the castle. Fortunately, wiser heads prevailed, Brahe and Kepler made up, and Kepler returned together with his family in tow.
Nevertheless, in 1601, there was an enormous plot twist: After a period of particularly heavy partying, Brahe died. On the time, his death was blamed on a kidney stone, but within the Nineties, it was suggested that Brahe could died from mercury poisoning, with Kepler a suspect in Brahe’s death. Nevertheless, in 2010, Brahe’s stays were exhumed, and a toxicology report found no evidence of mercury poisoning. As an alternative, it is assumed that Tycho died from a bacterial infection, prostate cancer or a burst bladder.
When did Kepler die?
Kepler died from a fever, possibly the results of a bladder infection, on Nov. 15, 1630, at age 58, in Regensburg, Germany.
Nevertheless, his name without end lives on, in each his laws of planetary motion and NASA’s Kepler space telescope, which discovered hundreds of exoplanets between 2009 and 2018.
Kepler’s three laws of planetary motion
Upon Tycho’s death, Kepler replaced him because the Imperial Mathematician to the Holy Roman Emperor, Archduke Ferdinand. On his deathbed, Brahe had permitted Kepler to make use of his preciously guarded astronomical data, and these data proved vital within the work that Kepler is best known for: his three laws of planetary motion.
In 1609, Kepler published “Astronomia Nova,” which detailed his 10-year-long study of the motion of Mars within the sky. “Astronomia Nova” contained the primary two laws; the third law was published in “Harmonices Mundi.” Then, in 1621, Kepler published his magnum opus, “Epitome Astronomiae,” which described all three laws in full.
Remarkably, without knowledge of the force of gravity that governs the orbits of the planets, Kepler had provided the fundamental mathematics of orbital motion. They were later developed further by Isaac Newton, who’s credited with “discovering” gravity, and Kepler’s laws were fundamental to Newton’s laws of gravitation.
The laws of planetary motion weren’t the one valid scientific work conducted by Kepler. In 1604, he published “Astronomiae Pars Optica” (“The Optical A part of Astronomy”), which explained why the lunar eclipse he had seen in 1580 was red (the results of atmospheric refraction of sunlight). In 1604, he witnessed a supernova within the constellation Ophiuchus, the serpent bearer, which was the last supernova seen within the Milky Way.
After the invention of the telescope in 1608, Kepler experimented with telescopic optics, improving upon the designs of Hans Lippershey and Galileo Galilei to create the Keplerian telescope, which formed the premise of all modern refracting telescopes.
What’s the first law of planetary motion?
The primary law of planetary motion states that planets move in barely elliptical orbits — subtle ovals somewhat than circles. Moreover, it states that the sun is positioned at one focus of the ellipse. With a circle, there may be a middle that’s equidistant from all points on that circle. In contrast, an ellipse doesn’t have a middle that’s equidistant. As an alternative, an ellipse has two foci — one on either side of the middle — along the middle line linking the 2 widest parts of the ellipse. (This is known as the semimajor axis.) The sun is at considered one of these foci.
What’s the second law of planetary motion?
The second law of planetary motion pertains to how a planet orbits more slowly the farther it’s from the sun on its elliptical orbit. It states that for those who were to attract a line between a planet and the sun, this line would sweep out equal areas during equal amounts of time.
To grasp this concept, picture an ellipse with the sun at one focus, as described in the primary law, and draw an imaginary line from the sun to a planet on that ellipse. Now, imagine the planet moving along its elliptical orbit for a given period of time when it’s at the alternative side of the ellipse because the sun. Since it is farther from the sun, it’s moving more slowly. The road between the planet and the sun will make an angle covering a certain area of the ellipse. Now, picture the planet on the opposite side of the ellipse, closest to the sun, moving for a similar period of time. Here, it’s moving faster, and the angle it draws is larger. But since it is closer to the sun, it covers the identical total area.
What’s the third law of planetary motion?
The third law of planetary motion states that the square of a planet’s orbital period is proportional to the cube of the length of the semimajor axis of its orbit. It is a complex way of claiming that the period of time it takes for a planet to finish one orbit across the sun (i.e., its orbital period) is proportional to the semimajor axis of its elliptical orbit, which is the road that cuts through the middle of the ellipse and connects the 2 widest parts. A planet with a bigger semimajor axis will take longer to orbit the sun. In other words, Venus takes longer to orbit the sun than Mercury does, Earth takes longer than Venus, Mars takes longer than Earth, and so forth.
Johannes Kepler FAQs
What’s Kepler best known for?
Johannes Kepler was an astronomer best known for his three laws of planetary motion, which describe how the planets move in ellipses across the sun. His name can also be well-known because of NASA’s exoplanet-finding Kepler space telescope.
What did Kepler invent?
In 1611, Kepler invented a kind of telescope, now called a Keplerian telescope, that used a convex eyepiece lens to offer a large field of view, somewhat than the narrow field seen through Galileo’s concave-lens telescope. The Keplerian design became the premise for all future refracting telescopes
How old was Kepler when he died?
Kepler was 58, six weeks shy of his 59th birthday, when he died from a temporary illness in 1530 while on a visit to Regensburg, Germany.
Additional resources
Try this neat video from NASA describing Kepler’s laws of planetary motion. You can too learn concerning the NASA exoplanet-hunting space telescope that was named after Kepler. Discover more concerning the supernova that Johannes Kepler witnessed in 1604 at NASA’s website.
Bibliography
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