The Cosmic Distance Debate

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The Milky Way's size was one of the great puzzles of astronomy. It was laid to rest by innovative thinking and grand experiments.
Supplement the videos with "OpenStax Astronomy"
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25 The Milky Way Galaxy
The stars move in many ways. They are not fixed in the sky, but changes slowly over the centuries.
en.wikipedia.org/wiki/Milky_Way
The Milky Way
en.wikipedia.org/wiki/Sidereu...
Sidereus Nuncius
en.wikipedia.org/wiki/Thomas_...)
Thomas Wright
en.wikipedia.org/wiki/William...
William Herschel
en.wikipedia.org/wiki/Carolin...
Caroline Herschel
en.wikipedia.org/wiki/Univers...
Kant's "Universal Natural History and Theory of Heaven"
en.wikipedia.org/wiki/William...
William Parsons, 3rd Earl of Rosse
en.wikipedia.org/wiki/Alexand...
Alexander von Humboldt
en.wikipedia.org/wiki/Pierre-...
Pierre-Simon Laplace
en.wikipedia.org/wiki/Jacobus...
Jacobus Kapteyn
en.wikipedia.org/wiki/RR_Lyra...
RR Lyrae stars
• The globular cluster M...
The globular cluster M4 in the eyes of Kepler/K2
www.nasa.gov/mission_pages/ke...
Kepler Space Telescope
arxiv.org/pdf/astro-ph/031047...
"The RR Lyrae Distance to the Draco Dwarf Spheroidal Galaxy"
www.aavso.org/vsots_rrlyr
RR Lyrae (AAVSO)
en.wikipedia.org/wiki/Harlow_...
Harlow Shapley
en.wikipedia.org/wiki/Extinct...)
Interstellar Reddening
en.wikipedia.org/wiki/Annie_J...
Annie Jump Cannon
en.wikipedia.org/wiki/Henriet...
Henrietta Swan Leavitt
en.wikipedia.org/wiki/Cepheid...
Cepheid variable
en.wikipedia.org/wiki/Instabi...
Instability strip
en.wikipedia.org/wiki/Great_D...)
Great Debate
en.wikipedia.org/wiki/Heber_D...
Heber Curtis
en.wikipedia.org/wiki/Edwin_H...
Edwin Hubble
hubblesite.org/newscenter/arch...
Hubble viewing Hubble's Cehpeids
books.google.com/books/about/...
"The Realm of the Nebulae"
0:00 Introduction
0:53 The Distance Problem
1:27 Solar System Distances
2:19 Trigonometric Parallax Limits
3:27 Luminosity Distance
4:24 Standard Candles
6:16 Spectroscopic Parallax
7:54 The Cosmic Distance Ladder
9:58 The Starry Messenger
11:13 Thomas Wright (1750)
12:38 The Herschels Star Counts in 1785
14:46 Immanuel Kant's Theory of the Heavens
15:26 Spiral Nebulae
16:34 Island Universe Hypothesis
17:15 Nebular Hypothesis
18:37 The Kapteyn Universe
22:07 Periodic Variable Stars: RR Lyrae itself (AAVSO)
22:38 Periodic Variable Stars: RR Lyrae stars
25:36 Interstellar Reddening
27:07 The State of Affairs in the 1920's
28:32 Annie Jump Cannon and the "Computers"
28:52 Henrietta Swan Leavitt
29:22 Periodic Variable Stars: The Leavitt Relationship
31:53 An example Cepheid with a 10-day period
32:36 Periodic Variables: The Instability Strip
33:17 The Stepping Stone (i.e. Leavitt's Back)
34:07 The Shapley-Curtis Debate (1920)
35:28 The Battleground Questions
36:18 Shapley's Arguments
37:26 Curtis Arguments
39:48 Edwin Powell Hubble Ends the Debate in 1923
44:57 The Realm of the Galaxies
45:56 The Milky Way
47:15 NGC 891: A Milky Way Analogue
50:22 Cosmic Distance Ladder...
51:39 REVIEW QUESTIONS