Galileo and Kepler

Galileo’s World at a Glance
Gallery at the Exhibit Website
Location: National Weather Center.

Who was Kepler, and why was a telescope named after him?

The Kepler space telescope launched in March, 2009, to search for terrestrial planets around other suns. One month later, five Jupiter-like planets had been discovered. As of 2015, the Kepler telescope has discovered a total of more than 1,000 confirmed planets. OU’s Kepler collection includes all 11 major works published during his lifetime and a large number of his minor works. In his immediate response to Galileo’s telescopic discoveries, Kepler suggested that unknown planets might exist, and might be inhabited.

Section 1: Kepler

Ancient Greek astronomy was based on the principle of uniform circular motion. Copernicus based his astronomical system on a strict enforcement of this principle, rejecting all compromises. For Galileo, also, planets moved in perfect circles. It is difficult today to imagine the hold which the ideal of uniform circular motion exerted upon the western astronomical tradition. In his “new astronomy,” Kepler employed motion that was neither circular nor uniform. Kepler’s bold originality disrupted the entire tradition of Greek astronomy from Plato to Copernicus and Galileo.

How vast and original Kepler’s contributions were, not only to astronomy but also in other fields, reaching to meteorology, mathematics, geology, mineralogy and crystallography. The German philosopher Immanuel Kant called Kepler “the most acute intellect” who ever lived. Kepler’s boundless curiosity, enthusiasm, originality, creativity and humble self-discipline shine through his works and make them a delight to read today.

1. Johann Kepler, Dissertatio cum Sidereo (Frankfurt, 1611), “Conversation on Galileo’s Starry Messenger”
2. John Wilkins, A Discovery of a New World… in the Moon (London, 1684)
3. Johann Kepler, Astronomia nova (Heidelberg, 1609), “The New Astronomy”
4. Johann Kepler, Dioptrice (Augsburg, 1611), “Optics of Lenses”
5. Johann Kepler, Strena, seu de nive sexangula (Frankfurt on Main, 1611), “On the Snowflake, or the Six-Angled Crystal”
6. Johann Kepler, Tabulae Rudolphinae (Gorlitz, 1627), “The Rudolphine Tables”
7. Johann Kepler, Wilhelm Schickard and Matthias Bernegger, Epistolae (Strasburg, 1672 & 1673), “Letters”
8. Johann Kepler and Jacob Bartsch, Admonitio ad astronomos (Frankfurt, 1630), “Admonition to Astronomers”
9. Maria Cunitz, Urania propitia (Oels, 1650), “The Generous Muse of the Heavens”

Further reading:

• Stillman Drake, Galileo: A Very Short Introduction (Oxford, 2001; originally printed 1983 in the Past Masters series), discussion guide.
• James Voelkel, Johannes Kepler and the New Astronomy (Oxford, 1999)
• Max Caspar, Kepler (Dover, 1993)

Curators: Kerry Magruder and Brent Purkaple. Links are to the Exhibit Guide, also available from the iBook Store. Open Educational Resources are available at lynx-open-ed.org and ShareOK.