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What would amaze a 16th century visitor?

Tycho Brahe (1543-1601) was an astronomer who made very high-precision pre-telescopic observations. His observations were good enough to show that comets don't have measurable parallax across the Earth's surface, making them farther than the Moon. He also observed a "new star" (nova, what we'd now call a supernova), and he found no measurable parallax for it also. So it was also farther than the Moon.

About geocentrism vs. heliocentrism, he proposed a compromise system where the Sun moved around the Earth and the other planets move around the Sun. He attempted to measure the parallax of the stars over each year, but he could not observe any. That parallax does exist, but it was too small for him to measure, and it was first measured in 1830.

Here is a history of theories from geocentrism to heliocentrism. What moves around the Sun?
[TABLE="class: grid"]
[TR]
[TD]Who
[/TD]
[TD]Me
[/TD]
[TD]Ve
[/TD]
[TD]Ea
[/TD]
[TD]Ma
[/TD]
[TD]Ju
[/TD]
[TD]Sa
[/TD]
[/TR]
[TR]
[TD]Ptolemy
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Capella
[/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Riccioli
[/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[TD][/TD]
[TD]X
[/TD]
[TD][/TD]
[TD][/TD]
[/TR]
[TR]
[TD]Tycho
[/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[TD][/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[/TR]
[TR]
[TD]Copernicus
[/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[TD]X
[/TD]
[/TR]
[/TABLE]
Capella was Martianus Capella, who worked around 410 - 420 CE. Ptolemy was Claudius Ptolemaeus (~100 - ~170 CE). Riccioli was Giovanni Battista Riccioli (1598-1671). Ptolemy's theory was the almost universal premodern one, and Copernicus's was anticipated by Aristarchus of Samos (~310 BCE - ~230 BCE).
 
I now turn to Johannes Kepler (1571-1630), a contemporary of Galileo.

He became convinced of heliocentrism, and in 1596, he published a book, "Mysterium Cosmographicum" (The Cosmographic Mystery), in which he proposed that the planets' orbits have size ratios equal to the inside-to-outside size ratios of the five Platonic solids:

Mercury - octahedron - Venus - icosahedron - Earth - dodecahedron - Mars - tetrahedron - Jupiter - cube - Saturn

He later rejected this scheme because the numbers don't work out very well.

From Sol Planetary System Data: Mercury 0.3870993, Venus 0.723336, Earth 1.000003, Mars 1.52371, Jupiter 5.2029, Saturn 9.537

[TABLE="class: grid"]
[TR]
[TD]Me[/TD]
[TD]Ve[/TD]
[TD]1.86861[/TD]
[TD]1.73205[/TD]
[/TR]
[TR]
[TD]Ve[/TD]
[TD]Ea[/TD]
[TD]1.38249[/TD]
[TD]1.25841[/TD]
[/TR]
[TR]
[TD]Ea[/TD]
[TD]Ma[/TD]
[TD]1.52371[/TD]
[TD]1.25841[/TD]
[/TR]
[TR]
[TD]Ma[/TD]
[TD]Ju[/TD]
[TD]3.41463[/TD]
[TD]3[/TD]
[/TR]
[TR]
[TD]Ju[/TD]
[TD]Sa[/TD]
[TD]1.83302[/TD]
[TD]1.73205[/TD]
[/TR]
[/TABLE]

General formula for outside/inside radius: sqrt(3)*tan(pi/n), where n = 3 for the tetrahedron, 4 for the cube and octahedron, and 5 for the dodecahedron and icosahedron. Written out, they are

3, sqrt(3), sqrt(3*(5 - 2*sqrt(5)))
 
Johannes Kepler then became Tycho Brahe's assistant, and he worked on Tycho's Mars data. He first discovered what became known as his second law of planetary motion, the equal-area law. It is equivalent to the law of conservation of angular momentum. He then considered the shape of the planet's orbit. It could not be a circle, because he was not successful in fitting the planet's orbit to a circle, and also because Tycho's observations were too good for that to be due to observational error. So he tried a lot of other shapes before finding the best fit: an ellipse with the Sun at one focus. That became his first law of planetary motion.

He also fixed the problem of the inclination of Mars's orbit. In Copernicus's theory, it wobbled a little bit, but Kepler showed that if one uses the Sun's true position rather than its average-motion position ("mean Sun"), as Copernicus did, the problem disappeared. "Copernicus didn't know his own riches!" he said about it.

He published his results in "Astronomia Nova" (The New Astronomy) (1609).

He got to work on the planets' orbits again, and he eventually discovered his third law: (period)^2 ~ (distance)^3. He published that in "Harmonices Mundi" (The Harmonies of the World) (1619). That relation turned out to be correct for moons of each planet, though with a different proportionality constant for each planet.

Among other things, he also noticed the hexagonal symmetry of snowflakes, and he conclude that snow was made of molecules that pack themselves in hexagonal fashion. He also invented a kind of telescope for astronomical work - one with two convex lenses instead of a convex then concave that Galileo had used. Galileo's design made images correctly oriented, while Kepler's made them upside down. Astronomers have found this being upside down tolerable ever since, and for Earthbound duty, one adds another lens to a Kepler-style telescope to flip the image yet again.
 
barbos said:
thebeave said:
barbos said:
Hell, It would have amazed 1980s barbos. I did not know about toilet paper, let alone soft one.
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Um...I'm almost afraid to ask the obvious question regarding pre-1980's barbos...
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Yes, we used news paper, and yes, I honestly did not know there was another way. The first time I saw toilet paper was in early 90s
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A lot of us might be using newspaper soon. I finally have an excuse not to throw out that old pile of newspapers.
 
blastula said:
barbos said:
Yes, we used news paper, and yes, I honestly did not know there was another way. The first time I saw toilet paper was in early 90s
Click to expand...

A lot of us might be using newspaper soon. I finally have an excuse not to throw out that old pile of newspapers.
Click to expand...

Why use it at all? I bought a bidet attachment for the toilet seat 7 years ago for $40. The only use of toilet paper now is a few squares to dab some water off. The bidet (with a helping hand) is 100% effective. And toilet paper isn't... So, talk about barbaric! Toilet paper is fucking medieval compared to a bidet.
 
Yeah, I've seen it's been a popular purchase lately, but I don't know if I'm ready to take that plunge just yet.
 
blastula said:
Yeah, I've seen it's been a popular purchase lately, but I don't know if I'm ready to take that plunge just yet.
Click to expand...

We have four bathrooms. We put Totos in the two that see the most use. The third would have been a pain to provide an electric outlet (as it is we hired an electrician--I would have no qualms about doing it myself if there were no drywall in the way, but doing it without drywall damage is a whole different thing) and the fourth is rarely used anyway. We love them.
 
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