Michael Mästlin

Kenny Smith

Mr. Percival

Pd. 0

16 Oct. 2009

Michael Mästlin

Michael Mästlin was a German astronomer who lived in the sixteenth and seventeenth centuries. Mästlin was born in the small town of Göppingen on September 30^th, 1550. He attended Tübingen University, where he would later go on to teach for 47 years. Mästlin taught a total of 51 years, including 4 years at the University of Heidelberg. Mästlin married Margarete Gruuninger, with whom he had six children. When she died, he remarried. His new wife was Margarete Burkhardt, the daughter of a professor at Tübingen, with whom he had eight more children. Mästlin would live until the age of eighty-one, dying on October 30^th, 1631.

Mästlin made a lot of contributions to astronomy. His excellent observational skills gained him fame throughout astronomical society. His observations of the supernova of 1572 and the comets of 1577 and 1580 helped establish new views that revolutionized the way that humans saw the universe. When he analyzed his observations of the nova of 1572, he found that they could only be explained by the assumption that the nova was as far away as the fixed stars that did not change position in respect to one another. This challenged the Aristotelian model of the universe, which stated that all changes in the universe were located closer to the Earth than the background stars that did not change positions. The significance of Mästlin’s findings caused his essay on the subject to be included in Tycho Brahe’s Progymnasmata. Mästlin’s accurate observations of two comets, those of 1578 and 1580, also led him to develop a ground-breaking idea. When he calculated the orbit of the comets he had been observing, his results showed that the comets orbited the sun, rather than Earth. Mästlin’s findings supported Copernicus’ heliocentric model of the universe. The comets’ orbits around the sun also went beyond the distance of the moon, which was another challenge to the geocentric system, which dominated the minds of people of the time. Although Mästlin’s approach to the problem was not firm, his new data added on to the already overwhelming evidence that had been gathering in favor of the heliocentric model of the universe. Based on Mästlin’s new found data and other convincing factors, Mästlin adopted Copernicus’ heliocentric view of the universe.

In 1582, Mästlin wrote his own textbook, Epitome Astronomiae. Although Mästlin was a proponent of the Copernican universe, he wrote his textbook based off of the Ptolemaic model. Copernicus’ ideas were still new to society and if Mästlin had written about them, it could have cost him his job. Mästlin used his textbook to teach his classes, so his classes were based primarily off of the geocentric model of the universe; however, when Mästlin taught more advanced topics and when students came to him for extra knowledge, he was more than willing to provide his students with his views on the heliocentric system.

This willingness is now what he is most famous for. Mästlin imparted his knowledge on a young man by the name of Johannes Kepler. Johannes Kepler created many influential ideas in the astronomical world, including his laws of planetary motion, which helped him become known as one of astronomy’s Big Five. Mästlin’s influence on Kepler led him to adopt Copernicus’ ideas. Mästlin was Kepler’s teacher at Tübingen University from 1589 to 1594. When Kepler sought extra knowledge from Mästlin, Kepler received lectures about how the heliocentric model of the universe was better than the accepted geocentric model. Mästlin showed Kepler how the data he had produced fit the heliocentric model of the universe much better than it did when it was plugged into the Aristotelian model. Kepler attributed his belief in Copernicus’ system to his teacher. The two men became great friends and communicated regularly after Kepler had moved on from the university.

Michael Mästlin is also known for a few other important findings. He is credited as being the first person to explain earthshine, which is the phenomenon that you can see the dark part of the moon because of the Earth’s reflection of sunlight in the direction of the moon. Mästlin is also attributed with being the first person to accurately calculate the golden ratio. In a letter to Johannes Kepler written in 1597, Mästlin states that the golden ratio has a value around 0.6180340. Modern thought even credits Mästlin with being responsible for Galileo’s heliocentric views of the universe, but this fact is still widely debated today.

Michael Mästlin’s impact on astronomy is truly revolutionary. From his amazingly accurate observations and calculations to his influence on his students, specifically Johannes Kepler, Mästlin has made an immense imprint on how we view the heavens today. Nobody knows what our views would currently be like if Michael Mästlin had not existed. Who knows how long it would have taken for heliocentricity to be adopted if it were not for Mästlin’s influence on the astronomy of his day. Michael Mästlin, although not always given the credit he deserves, is no doubt one of the most influential astronomers of all time.