This is the second lecture series of my complete online introductory undergraduate college course. This video series was used at William Paterson University and CUNY Hunter in online classes as well as to supplement in-person course material. 00:00:00 - lecture 1: Cosmic Distances using Parallax 00:17:49 - lecture 2: How do we know that the Earth is Round? 00:27:03 - lecture 3: How Big are the Sun and Moon? 00:36:23 - lecture 4: How Did Geocentrism Fail the Tests of Science? 00:54:14 - lecture 5: The Dawning of Astrophysics 01:16:20 - lecture 6: Galileo, the Father of Science 01:43:21 - lecture 7: Galileo's Legacy 01:56:01 - lecture 8: Newton's Laws, Orbits and Gravity 02:20:56 - lecture 9: A Safe Intro to Physics Equations 02:50:15 - lecture 10: "And Yet It Moves": Galileo Vindicated 03:08:28 - lecture 11: Wave Motions Everywhere 03:27:12 - lecture 12: The History of the Theory of Light 03:38:47 - lecture 13: Newton's Corpuscular Theory of Light: So Close, but So Far 03:51:44 - lecture 14: The End of Newton's Theory of Light In this lecture set, I set the stage with a discussion about finding distances to stars using parallax. To get those distances, we need to learn about the nature of the Earth being a sphere. Armed with that, we can address why geocentrism held sway for nearly 2000 years and why it was overthrown. Then, I discuss the accomplishments of Nicolas Copernicus, Tycho Brahe, and Johannes Kepler in the advancement of science. Then, I move on to the accomplishments (and failures) of Galileo Galilei, the Father of Modern Science. Next, we see the effect of Galileo's work around him and the work that surrounded him. Jeremiah Horrox predicted and observed a transit of Venus, the book Galileo should have written was finally done, the Geocentric model held its head up for one more fight, and the Leaning Tower of Pisa legend was born. This leads us to Newton's Laws of Motion and his Law of Gravity. We also talk about centers of mass and other things related to the understanding of orbits. They provide a framework for predicting the motions of the planets around the Sun. And how everything moves. Next, we take a diversion into the nature of mathematics. I find that a lot of people have a fear of math. I make it a point in my classes to overcome that fear if possible. After that, we discuss exactly how we know the Earth moves. We learn about parallax and stellar aberration. Finally, we can say for certain that the Earth moves, even though we don't feel it. Thus science gives us one of the first answers that goes against "common sense," but is nonetheless true. Overall, the segment emphasizes clear definitions, underlying geometry, and practical observing guidance so viewers can connect the concept to the real sky.