1. Announcements 1 st Quarter Observing Night Wednesday night. Set-up starts at 6:45pm. We will be in the SSC Atrium as the temperature will be too cold to be outside. If the skies are clear we will set-up a couple of Dobs outside for a quick look.

2. Nicholas Copernicus 1473 – 1543 The Sun is the center Mathematical model no better than Ptolemy’s Model had predictive power Watch video from Museo Galileo on the Copernican System

3. The Copernican Universe The Sun is at the center of the solar system and Earth is just another planet going around it. The only thing that goes around Earth is the Moon.

4. Copernicus publishes his book in the year he dies De Revolutionibus Orbium Coelestium is published in 1543 and the first printing is delivered to him on his death bed. He had delayed publication for fear of excommunication. Original foreword by a local priest claimed that Copernicus didn’t really believe the Sun was the center, just that it was a mathematical model.

5. Tycho Brahe: last great naked-eye astronomer 1546 – 1601 Made detailed observations of Mars Observed a “nova stella” Doesn’t believe in the Copernican model but doesn’t like the Ptolemaic model either.

6. The Tychonic Solar System

7. Tycho’s Uraniborg and Stjerneborg

8. Tycho’s Mural Quadrant Tycho directs while his apprentices make the observation, read the scale and record the measurements. Others work elsewhere on calculations and instrument making

9. Johannes Kepler 1571 – 1630 Hired by Tycho Brahe in 1600 to do calculations on the orbit of Mars Appointed Imperial Astronomer after Tycho’s death

10. Rudolphine Tables As part of his duties as the Astronomer Royale for the Holy Roman Emperor, Kepler was to recalculate the positions of the planets. He did so using his three Laws of Planetary Motions. The book was eventually published in 1627 after several legal battles with Tycho’s heirs

11. Watch Mechanical Universe Kepler’s Laws video

12. Kepler’s 1 st Law The planets move in elliptical orbits with the Sun located at one focus The Law of Ellipses Major change since everyone that came before had used circles, including Copernicus

13. Kepler’s 2 nd Law A line drawn from a planet to the Sun will sweep out equal areas in equal time periods The Law of Areas

14. Kepler’s 3 rd Law The Law of Harmonies The ratio of the square of the orbital period to the cube of the orbital semimajor axis (the radius) is the same for all the planets

15. Galileo Galilei 1564 – 1642 First to turn the telescope skyward Developed new physics to replace the physics of Aristotle Got into deep trouble with the Catholic Church

16. Galileo’s first major discovery concerned the planet Jupiter Over a week long period in January 1610 he makes observations that prove the existence of four moons orbiting Jupiter.

17. Another of his observations that support the Copernican views is the phases of Venus

18. In late 1632, Galileo’s book is banned and he is put on trial by the Inquisition In late 1632, Galileo’s book Dialogues is banned and he is put on trial by the Inquisition

19. In June 1633 he is found guilty and sentenced to prison. After recanting his views, his sentence is commuted to house arrest

20. If you ask a physicist, Galileo’s most important contributions were in mechanics