Astronomers In the 1500s Ashlie Keller P.5

On the left is a sculpture of Galileo, the middle is a bust Kepler, and the right is Copernicus

Astronomy played a big role in the 1500s-1600s. The lives, education, and observations of Galileo, Copernicus, and Kepler has impacted even the most modern astronomy.

Galileo Galilei

Quote #1: “Galileo Galilei was born in Pisa on Feb. 15, 1564. In the early 1570's, his family moved to Florence. Galileo began his formal education at a school in a nearby monastery. Galileo's father was determined that his son should be a doctor. The boy's family sent him to the University of Pisa in 1581. Galileo studied medicine and the philosophy of Aristotle for the next four years”

Commentary : Galileo is born on Feb. 15, 1564 in Pisa, Italy. Later, his family moved to Florence, Italy. His education began at a school in a monastery (a building or buildings occupied by a community of monks living under religious vows). He attended the University of Pisa in 1581 and studied medicine and the philosophy of Aristotle. Galileo´s education impacted the his life and his accomplishments. Without proper education, Galileo would be enable to have knowledge.

Quote #2: "Galileo published his results in a book called The Starry Messenger in 1610. The Starry Messenger became one of the most important books of the seventeenth century...It contained descriptions of what he saw on the moon's surface. In it he listed his observations of the stars in the Milky Way...He named his newly discovered moons "Medicean stars", in honor of Cosimo de Medici".

Commentary: In Galileo's new book, he explains his most recent observations like the moon and the Milky Way and became one of the most important books in his time. In Galileo's new book, he explains his most recent observations like the moon and the Milky Way and became one of the most important books in his time.

Quote #3: “Galileo used the appearance of the supernova to openly declare that Aristotle's theory of an unchangeable universe could not possibly be correct. He gave three lectures about the star, saying it provided proof that Aristotle was wrong”.

Commentary: Galileo questioned an ancient philosophers work, quite a bold move. Though it sparked some controversy in the society, Galileo turned out to be correct. He proved that the stars and planets do indeed move. With Galileo's confidence to prove a famous philosopher wrong, paved a path for future astronomers to question all theories.

Quote #4: "Using his telescope, Galileo observed several previously undiscovered stars, and spotted Jupiter's four largest, brightest satellites, proving that not all heavenly bodies revolved around the earth....After his discovery of spots on the sun, and his observation that the spots appeared to have moved when viewed at different intervals, Galileo believed he could prove that the sun rotated on its axis, and was not immovable”.

Commentary: Galileo observed Jupiter's moons, and the spots on the sun. He saw that these spots were indeed moving in intervals. Galileo's observations were the first of many, and he drew many conclusions we that turned out to be true.

Nicolaus Copernicus

Quote #5: “Copernicus was born on Feb. 19, 1473, in Thorn (now Torun, Poland). He entered the University of Kraków in 1491 and studied there for four years. In 1496, he began studying church law at the University of Bologna in Italy. He pursued astronomy on his own time, making his first recorded astronomical observation in Bologna in 1497...Copernicus studied medicine in Italy at the University of Padua from 1501 to 1503. He received a degree in church law from the University of Ferrara in 1503”.

Commentary: Nicolaus attended 2 universities. While studying Church Law, on his own time, he studied astronomy. He made his first recorded observation while attending Bologna University. He also studied medicine at the University of Padua. Copernicus studied many professions and studied in numerous universities. He held a great amount of knowledge from all the schools he attended. Without such education, he would be incapable to make the discoveries he did in his lifetime.

Quote #6: "...he showed that a cosmology in which Earth and the planets rotate about the Sun offered a simpler explanation of planetary motions than the geocentric model of Ptolemy, which had been universally accepted for well over 1000 years. He circulated his preliminary ideas privately in a short manuscript in 1514 and continued to develop the theory over the next 30”.

Commentary: Nicolaus made the observation that the planets rotated the Sun. This made much more sense and was much simpler than the geocentric model of Ptolemy. He kept his ideas in a manuscript that sculpted his theory over the next 30 years. This observation of the planets was one of the first of Copernicus. Without such an open-minded, isolated ideas, we could still be questioning planetary movements today.

Quote 7:"...[Copernicus] wrote an essay that has come to be known as the 'Commentariolus,' [which] introduced his new cosmological idea, the heliocentric universe..."Commentariolus," or "Little Commentary," was first circulated in 1514, and included Copernicus's famous seven axioms:

There is no one center in the universe.

The Earth's center is not the center of the universe.

The center of the universe is near the sun.

The distance from the Earth to the sun is imperceptible compared with the distance to the stars.

The rotation of the Earth accounts for the apparent daily rotation of the stars.

The apparent annual cycle of movements of the sun is caused by the Earth revolving round it.

The apparent retrograde motion of the planets is caused by the motion of the Earth from which one observes”.

Commentary: Copernicus had ideas he formulated ideas he called "commentariolus". These included that there is no center of the universe, Earth is not the center, rotation on Earth is a daily occurrence, ect. With his 7 famous axioms afloat many people at the time doubted and criticized these ideas. However, many of them eventually were proven true and still stood by today.

Johannes Kepler

Quote 8: "Kepler, Johannes (yōhä′nəs kĕp′lər), 1571–1630, German astronomer. From his student days at the Univ. of Tübingen, he was influenced by the Copernican teachings. From 1593 to 1598 he was professor of mathematics at Graz and while there wrote his Mysterium cosmographicum (1596). This work opened the way to friendly intercourse with Galileo and Tycho Brahe, and in 1600 Kepler became Tycho's assistant in his observatory near Prague... In 1612, becoming mathematician to the states of Upper Austria, he moved to Linz".

Commentary: Kepler was a German astronomer who was influenced by Copernicus's teachings. He became a professor in math at Graz University and wrote a book called Mysterium Cosmographicum. He became friendly and worked with Galileo and Tycho Brahe, and later become Brache's assistant. He then became a mathematician to the states of Upper Austria. Kepler was given many opportunities to work with successful astronomers and received a very good education. This influenced him to make great discoveries in later life.

Quote #9: "Kepler's laws describe the motions of the planets around the sun. His first law states that every planet follows an elliptical (oval-shaped) path, or orbit, around the sun. The shape of such a path, called an ellipse, is determined by two points on either side of its center, called foci (singular, focus). The first law states that the sun lies at one focus of each elliptical orbit".

Commentary: Kepler's first law suggests that every planet orbits the sun in an elliptical shape. Though, he has 3 main laws that all have to do with the sun and the planets that orbit it. Kepler's first law that marked the starting point of history. This was his initial thought that lead him to more accurate observations, theories, and eventually, laws.

Quote #10: "Kepler believed that the sun did not sit passively at the center of the solar system but that through some mysterious power or "virtue" actually compelled the planets to hold to their orbits.... Newton assumed that the sun continuously exerts a force on each planet that pulls the planet toward the sun. He calculated that elliptical orbits would result if the force varied inversely as the square of the distance from the sun... His law of universal gravitation predicts that the planets exert small forces on each other although subject to the dominant force of the sun. These small additional forces explain most of the small departures from Kepler's laws revealed by later, more accurate observations".

Commentary: Kepler thought the sun was not the center of the solar system, but that a higher power compelled the planets to hold their orbits. Not gravity. However, Kepler's thoughts differed from Issac Newton's which suggested that the Sun exerted a force like gravity to keep the planets orbiting. Kepler was obviously proven wrong from on his idea about the sun, but he made many more discoveries that make up for it. Without this little fault, it could have affected his entire discovery of laws.

Works Cited

Doak, Robin S. Galileo: Astronomer and Physicist. Minneapolis, Compass Point Books, 2005.

Findlen, Paula. “Galileo.” World Book Advanced. World Book, 2016. Web. 6 Dec. 2016

Hightower, Paul. Galileo: Astronomer and Physicist. Springfield, Enslow Publishers, 1997.

History Reference Center. “Johannes Kepler.” Columbia Electronic Encyclopedia, 6Th Edition (2016): 1. History Reference Center. Web. 8 Dec. 2016.

History Reference Center. “Kepler’s Laws.” Columbia Electronic Encyclopedia, 6Th Edition (2016): 1. History Reference Center. Web. 8 Dec. 2016.

History Reference Center. Ryan, James. “Galileo Galilei.” Galileo Galilei (2005): 1-2. History Reference Center. Web. 8 Dec. 2016.

History Reference Center. Shaer, Matthew. “How Nicolaus Copernicus rewrote the rules of the solar system.” Christian Science Monitor 19 Feb. 2013: N.PAG. History Reference Center. Web. 8 Dec. 2016.

Sirs. “Nicolaus Copernicus: The Man Who Changed the Cosmos (1473 A.D.....” Truth Seeker Vol. 128, Millennium Issue Part 1. Dec. 2001: 114-116. SIRS Renaissance. Web. 08 Dec. 2016.

World Book. Findlen, Paula. “Copernicus, Nicolaus.” World Book Advanced. World Book, 2016. Web. 9 Dec. 2016.

World Book. Findlen, Paula. “Kepler, Johannes.” World Book Advanced. World Book, 2016. Web. 9 Dec. 2016.

Created By
Ashlie Keller


Created with images by Norman B. Leventhal Map Center at the BPL - "Cosmographia."

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