The Extragalactic Distance Scale

We use many tools to get us out to the farthest reaches of the Cosmos. Herein, we summarize the various ways we learn to measure these gargantuan lengths, using the Cosmic Distance Ladder. This is part of my complete intro Astronomy class that I taught at Willam Paterson University and CUNY Hunter. When I originally recorded this in 2018, the Hubble Tension was only just beginning. Now, it's coming to a head, and causing lots of issues....
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0:00 Introduction
3:01 Hubble's Law
4:00 Steps to Find the Hubble Parameter Ho
5:25 More on the Leavitt P-L Relationship
7:09 Steps up the Cosmic Distance Ladder
7:41 The Astronomical Unit
8:51 Trigonometric Parallaxes
9:57 Spectroscopic Parallaxes
11:49 Cepheid Variable Stars
14:10 Step 5: Galaxy Standard Candles: Desperation....
15:24 Luminosities of Entire Galaxies
18:57 The Tully-Fisher Relation for Spiral Galaxies
21:48 Redshift Distances
23:11 Critical Measurements for the Cosmic Redshift
24:51 There are still things to work out with H.
27:24 The Big Questions