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Now that everyone's got their eyes on Saturn: we're pretty lucky to be seeing Saturn at this angle during the conjunction with Jupiter, so we can actually see its rings through a telescope. For a while, nobody knew what to make of Saturn's bizarre shape-shifting. (1/n)
In the early 17th century (e.g., the beginning of telescopic astronomy), Saturn posed a bit of a mystery, appearing differently shaped at different times. Astronomers were perplexed about Saturn's apparent "ears" or "handles." (2/n)
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![In the early 17th century (e.g., the beginning of telescopic astronomy), Saturn posed a bit of a mystery, appearing differently shaped at different times. Astronomers were perplexed about Saturn's apparent "ears" or "handles." (2/n)[expand the thumbnail for the full selection]](https://pbs.twimg.com/media/Epx0bA9XUAUo6ys.png "In the early 17th century (e.g., the beginning of telescopic astronomy), Saturn posed a bit of a mystery, appearing differently shaped at different times. Astronomers were perplexed about Saturn's apparent \"ears\" or \"handles.\" (2/n)[expand the thumbnail for the full selection]")
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Astronomers debated whether Saturn was one large body orbited by two smaller ones, or if it was ellipsoidal in shape, or if it was a normal planet with strange crescents attached on either side. (3/n)
One Jesuit astronomer, Honoré Fabri, believed Saturn was orbited by two large (but dark) nearby satellites, and two smaller but brighter distant satellites, accounting for its strange changing shape. 4/n
In 1655, Christiaan Huygens posited that Saturn was surrounded by a detached ring, which depending on the angle of view from Earth would appear as ears, a handle, orbiting satellites, etc.
Many found that difficult to believe, and needed more evidence. (5/n)
Many found that difficult to believe, and needed more evidence. (5/n)
Leopoldo de' Medici wanted the dispute settled, so in 1660 he invited the Accademia del Cimento to figure it out. They built a model of Saturn with rings at the end of a long dark hallway, illuminating the model itself with torches. They placed telescopes at the other end. (6/n)
Observers were invited to look through them; one telescope was cruddy, the other was pretty good. Through the cruddy telescope, observers reported seeing an oblong shape, three small spheres, and other observations consistent with the various Saturn-shape hypotheses. (7/n)
This clever experiment didn't *prove* Saturn had rings, but it did show that Huygens' hypothesis of Saturn having rings would be consistent with observations. The matter was shortly settled. (8/9)
The story itself is great, but I particularly love how a model suggests the credibility of a hypothesis.
Historians can learn from this. See my many-year-old blog post ( http://scottbot.net/digital-history-saturns-rings-and-the-battle-of-trafalgar/) and co-authored piece with @electricarchaeo ( https://link.springer.com/article/10.1007/s10816-014-9230-y) for more! (9/9)
Historians can learn from this. See my many-year-old blog post ( http://scottbot.net/digital-history-saturns-rings-and-the-battle-of-trafalgar/) and co-authored piece with @electricarchaeo ( https://link.springer.com/article/10.1007/s10816-014-9230-y) for more! (9/9)
P.S. if you wonder why astronomers called them Saturn's "ears," see Exhibit A.
oooh here's a great photo from today with a slightly worse telescope that illustrates Saturn's ears/handles particularly well (h/t @beckyfh): https://twitter.com/SV8QG/status/1341080888323547144
Alex's photo from the previous tweet looks a lot like the sketch from Galileo's 1623 "Il Saggiatore."
And isn't it everyone's lucky day? It looks like there's a new biography of Christiaan Huygens! (h/t @rmathematicus). What a convenient conjunction. https://twitter.com/TFr68/status/1341071733638500353
