Uploaded April 2021 | Updated September 2026, 2 weeks ago

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Alan's links:
Orbits: nasa.gov/audience/forstudents/5-8/features/nasa-knows/what-is-orbit-58.html
Gravity: spaceplace.nasa.gov/what-is-gravity/en
Dark Matter: nasa.gov/audience/forstudents/9-12/features/what-is-dark-matter.html
Proof of Dark Matter: nasa.gov/vision/universe/starsgalaxies/dark_matter_proven.html
Light-year: spaceplace.nasa.gov/light-year/en
Gravitational lensing: jpl.nasa.gov/images/gravitational-lensing-graphic

jump ahead:
@1:33 Alan's Links
@2:02 Alan's Summary of Gravity
@15:09 Question #1
@23:12 Question #2
@27:37 Question #3
@36:40 Question #4
@46:06 Question #5
@50:31 What would jumping off a rotating sphere be like?
@55:57 Question #6
@1:08:40 What is too small to see?
@1:14:21 Summary

source material:
Orbits Diagram
mk0astronomynow9oh6g.kinstacdn.com/wp-content/uploads/2015/12/outer_solar_system_1097x1097.jpg

Multiple Coins Inside A Coin Vortex Funnel
By Klip
youtu.be/2xQ_vcGgwOU

Thomas Kuhn
Stanford Encyclopedia of Philosophy
https://plato.stanford.edu/entries/thomas-kuhn/

Astronomy Picture of the Day May 24, 2006
apod.nasa.gov/apod/ap060524.html

The Unaided Eye
by Ben Burress
kqed.org/quest/236/the-unaided-eye#:~:text=The%20most%20distant%20individual%20star,more%20luminous%20than%20our%20Sun.

Flat Earther | ISS is a hologram
Creaky Blinder
youtu.be/gFRYosCPJTE

muppets tonight - sandra bullock & kermit - phenomena
Christian Helmreich
youtu.be/lxmP01HERnQ