Lecture 22: The Cosmic Distance Problem
How do we measure distances to astronomical objects that are too far\naway to use Trigonometric Parallaxes? This first lecture of Unit 4\nreviews geometric methods like trigonometric parallaxes, and then\nintroduces the idea of Standard Candles, and how they are used to\ndevelop methods for deriving Luminosity Distances based on the Inverse\nSquare Law of Brightness. We will explore three luminosity-based\ndistance methods useful for studying our Galaxy and nearby galaxies:\nSpectroscopic Parallaxes, Cepheid Variable Period-Luminosity Relation,\nand the RR Lyrae P-L Relation. Recorded 2006 February 6 in 1008 Evans\nLaboratory on the Columbus campus of The Ohio State University.