Terence Tao on the cosmic distance ladder

The Cosmic Distance Ladder: How we learned distances in the heavens. Next part: https://youtu.be/hFMaT9oRbs4 Patreon supporters see early views of new videos: https://www.patreon.com/3blue1brown Artwork by Kurt Bruns Thanks to Paul Dancstep for several animations, such as the powers of 10 zoom out and the simulations of shadows on the moon. Terry has kindly cataloged many of the added nuances, including a few corrections, in this post: https://terrytao.wordpress.com/2025/02/13/cosmic-distance-ladder-video-with-grant-sanderson-3blue1brown-commentary-and-corrections/ As an additional one, the portrait shown for Kepler, despite being somewhat widespread, actually turns out not to be Kepler. See this article by Václav Pavlík https://ui.adsabs.harvard.edu/abs/2021PhT....74i..10S/abstract Also, although the Earth is about 4 times as wide as the Moon, as it happens, you would not see this with the lunar eclipse composites, since the umbra of Earth's shadow from the sun is sufficiently smaller than the Earth out where the Moon is. Moon composite shot by Reddit user _wanderloots: https://www.reddit.com/r/astrophotography/comments/yil0tu/partial_lunar_eclipse_composite/ https://youtube.com/@Wanderloots Thanks to Tanya Klowden for helpful conversations about the history of the distance ladder. Argument for why if every shadow of a convex shape is a circle, it must be a sphere: https://mathoverflow.net/questions/39127/is-the-sphere-the-only-surface-with-circular-projections-or-can-we-deduce-a-sp Timestamps: 0:00 - About Terence Tao and the Distance Ladder 2:02 - Earth 8:07 - Moon 11:15 - Sun 15:45 - Heliocentrism in Antiquity 18:27 - Kepler’s genius 27:16 - Where this leaves us SEV #5: https://youtu.be/uq83hprtpGE ------------------ These animations are largely made using a custom Python library, manim. See the FAQ comments here: https://3b1b.co/faq#manim https://github.com/3b1b/manim https://github.com/ManimCommunity/manim/ All code for specific videos is visible here: https://github.com/3b1b/videos/ The music is by Vincent Rubinetti. https://www.vincentrubinetti.com https://vincerubinetti.bandcamp.com/album/the-music-of-3blue1brown https://open.spotify.com/album/1dVyjwS8FBqXhRunaG5W5u ------------------ 3blue1brown is a channel about animating math, in all senses of the word animate. If you're reading the bottom of a video description, I'm guessing you're more interested than the average viewer in lessons here. It would mean a lot to me if you chose to stay up to date on new ones, either by subscribing here on YouTube or otherwise following on whichever platform below you check most regularly. Mailing list: https://3blue1brown.substack.com Twitter: https://twitter.com/3blue1brown Instagram: https://www.instagram.com/3blue1brown Reddit: https://www.reddit.com/r/3blue1brown Facebook: https://www.facebook.com/3blue1brown Patreon: https://patreon.com/3blue1brown Website: https://www.3blue1brown.com