This is part of my complete intro Astronomy class that I taught at Willam Paterson University and CUNY Hunter. If you want to watch all the videos in the correct order, please visit my website at The stars move in many ways. They are not fixed in the sky but changes slowly over the centuries. Supplement the videos with "OpenStax Astronomy" 3.3: Newton's Universal Law of Gravitation 17: Analyzing Starlight 18: The Stars, a Celestial Census 19: Celestial Distances Proper Motion Radial Velocity Space Velocity Parallax Barnard's Star The Hyades Dark Matter from Galaxy Rotation Curves Jack Schmidling's view of Barnard's Star Radar Mapping of Venus 0:00 Introduction 2:33 Stellar Parallax 3:58 A star at a far distance 4:27 Parallax is defined to be half of the total shift 4:43 The definition of parallax distance 5:39 The Phases of Venus and the Distance to the Sun 7:26 Parsec Definition 10:14 Proper Motion: Stars moving across the sky 13:05 Proper Motion of the Hyades 15:41 Proper motions are cumulative 17:46 Case Study: Proper motions in the Big Dipper 19:52 Proper Motion depends on the Distance 21:10 Radial Velocity 24:03 True Space Motions 26:37 Why measure the space motions?