Part 1: Astronomy: How our understanding of the universe has changed• In the 2nd century Claudius Ptolemy devised an ‘earth centered’ or

geocentric astronomical model of the known planets and stars.• His theories were a refinement of other Greek astronomers ideas of the solar

system. (Iowa State, 2001)

• 1542: Nicolaus Copernicus published his definitive work on a ‘sun centered’ or heliocentric astronomical model.• The orbits of the planets were equally spaced and mathematically measured.

(Weisstein 2007)

• Further observations of the stars and the planets expanded our knowledge of our solar system and galaxy. (Riebeek, 2009)

Example 1: Earth Central. Ptolemy and the Geocentric Universe• Circa 140 C.E. Ptolemy, (Latin

name Claudius Ptolemaeus), theorized that the Earth was the center of the Universe. (Academic)

• Each planet revolved around the Earth on its own orbit, or epicycle.

• The Ptolemic system was accepted for 1,300 years.

Claudius Ptolemy (1475, Van Gent)

Example 2: Seeing the Light. Copernicus and the Heliocentric System• 1508 Nicolaus Copernicus began

developing his own celestial system: A Heliocentric system. (Biography 2015)

• The Planets moved in a circular pattern around the sun. The size of each planet’s orbit depended on its distance from the sun. (A controversial claim at the time!)

• 1514, he distributed The Little Commentary, which contained the Seven Axioms.

• 1543, On the Revolutions is published. (NM, 2015)

Nicolaus Copernicus (Artist unknown, Viola 2014)

Example 3: The Universe Comes into Focus. Galileo Galilei and the Telescope• Through the use of his telescope,

Galileo discovers the surface of the moon is rough. (Disproving the Aristotelian belief that the heavens were perfect).

• Observes the orbits of the four moons of Jupiter. Proving that orbiting moons, would not be left behind if a celestial body moved through space. (A Ptolemaic argument).

• Saw the phases of Venus. This observation provided further proof that the sun was central to the system and not the Earth. (Iowa State 2001)

Galileo Explaining Lunar Topography to Two CardinalsJean Leon Huens, 1857 (Awesome)

Part 2 Historical Event: The Publication of Johannes Kepler’s Astronomia Nova and Harmonices Mundi

• The first two laws of planetary motion were published in 1609 in Prague.

• Continuing his work, Johannes Kepler discovered the third law of planetary motion on May 15, 1618. One year later he published Harmonices Mundi (NASA, 2013)

The World in the Year 1609

• May 20, William Shakespeare’s Sonnets published in London(Historyorb, 2015)

• Aug. 25, Galileo demonstrates his first telescope to the Venetian lawmakers (Historyorb, 2015)

• Sept. 4, Henry Hudson becomes the first European to discover the island of Manhattan (Historyorb, 2015)

Shakespeare, (Tudor)

Hudson, (Historyorb, 2015)

Impact of Kepler’s Laws

• While Kepler’s work was not widely accepted at first, Galileo ignored his writings, the work Kepler did in the fields of optics legitimized Galileo’s own work with telescopes. (Science, 2015)

• Shortly after Kepler’s death, Pierre Gassendi and Jeremiah Horrocks, observed the transits of Mercury in 1631 and Venus in 1639. Confirming predictions Kepler had made about their orbits. (Science, 2015)

• It was the third law of planetary motion, not the proverbial apple, that led Sir Isaac Newton to the law of gravity. (NASA, 2013)

Supporting Example 1

• Kepler’s analysis of Brahe’s observations of Mars led him to the discovery of the first law: Planets move in ellipses with the Sun at one focus. (NASA, 2013)

• The textbook, Epitome of Copernican Astronomy, was widely read for twenty years after Kepler’s death. It contained his works on the elliptical orbits of planets and many other discoveries made by Kepler. (Science, 2015)

Supporting Example 2

• Prior to the discovery of the first law, Kepler observed what would become the second law: The radius vector describes equal areas in equal times. (NASA, 2013)

• All three of Kepler’s laws, from their inception to the present, have retained their voracity. (Science, 2015)

Works Cited

• http://www.polaris.iastate.edu/EveningStar/Unit2/unit2_sub1.htm

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• http://scienceworld.wolfram.com/biography/Copernicus.html © 1996-2007 Eric W. Weisstein

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• http://earthobservatory.nasa.gov/Features/OrbitsHistory/ Holli Riebeek Design by Robert Simmon July 7, 2009

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• http://academic.emporia.edu/abersusa/students/denning/geo.htm

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• https://themathematicaltourist.wordpress.com/tag/pappus/

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• http://viola.bz/nicolaus-copernicus-540/

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• http://www.biography.com/people/nicolaus-copernicus-9256984#heliocentric-solar-system

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• http://www.nmspacemuseum.org/halloffame/detail.php?id=123

Works cited

• https://www.awesomestories.com/asset/view/Galileo-with-two-Cardinals

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• http://www.polaris.iastate.edu/EveningStar/Unit2/unit2_sub5.htm

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• http://kepler.nasa.gov/Mission/JohannesKepler/#anchor784359

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• http://www.historyorb.com/events/date/1609

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• http://tudorhistory.org/people/shakespeare/

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• https://thescienceclassroom.wikispaces.com/Johannes+Kepler