On 21 December 2020, astronomers around the world will have the opportunity to observe one of the long running "Great Conjunctions" between Jupiter and Saturn which occurs every twenty years. This even has more historical and astrological significance than importance to the modern study of astronomy and astrophysics. Yet few textbook even mention this phenomenon or the long record of observations extending back well over a thousand years.
This talk will provide an explanation of the underlying physical causes of this twenty year occurrence and the reason for the next conjunction in the sequence being shifted approximately 120 backwards along the ecliptic. Additionally, it will provide an observer's guide to witnessing this year's optical conjunction on December 21st.
Next, this talk will link the long series of Great Conjunctions to an event in the life of Johannes Kepler when, in 1595, he thought he had quite by accident discovered an insight to God's line of reasoning for creating a solar system with just six planets. Kepler's interest in the Great Conjunctions persisted and in 1603 he coined the term: "fiery trigon" and drew a diagram of it in his book: De Stella Nova.
Finally, Kepler was so inspired with his 1595 revelation that he wrote his first major book on astronomy: Mysterium Cosmographicum (c. 1596), which is important because it caught the eye of Tycho Brahe and later led to the two of them becoming colleagues.
Zoom link: https://umsystem.zoom.us/j/94617117774 (Meeting ID: 946 1711 7774)