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Punch it, SpaceX
She’s not looking up at the sky; she’s looking down at it. I am excitedly following the Inspiration4 spaceflight and its diverse all-private crew of Jared Isaacman, Sian Proctor, Christopher Sembroski, and Hayley Arceneaux. Orbiting higher than any humans this millennium and carrying the largest window ever flown in space, their Crew Dragon Resilience is providing unprecedented and…
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Dandelin Spheres
In 1609, Johannes Kepler first described how planets orbit the sun in ellipses. Kepler understood an ellipse as both the locus of points whose distances from two foci sum to a constant and as the intersection of a cone and a plane. But how are these familiar definitions equivalent? In 1822, Germinal Dandelin discovered a beautiful construction that proves this…
Month: September 2021
Recent Comments
Nice post, John! Thanks for writing these. I always enjoy them.
David Smith’s ein stein is an awesome shape!
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- Sabbatical trip to Europe – Part 3 (Otto Rössler)
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- Where Are the Stars?
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Thanks, Mark! I enjoy reading your posts as well.