Episode #125 of the Stack Overflow podcast is here. We talk Tilde Club and mechanical keyboards. Listen now
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It happened long before Newton. In the second century BC Hipparchus used lunar parallax to calculate a value for the minimum and maximum distance of the earth and moon. His results are very close to the modern calculation of this distance. You can read about it here: Toomer G.J. (1974), "Hipparchus on the Distances of the Sun and Moon." Archives for the ...


16

It is a funny story, a comedy of errors, that started with Kepler and Galileo, and was likely picked up by Swift as a target of satire. It is assumed that Voltaire followed Swift, but it paid off for both, two Martian craters are now named after them. How ironic if the 'prediction' was indeed meant as a mockery. Another irony is that perhaps Swift should not ...


15

As quoted from this article: Many people's work was needed to prove that the Sun is a star. The first person we know of to suggest that the Sun is a star up close (or, conversely, that stars are Suns far away) was Anaxagoras, around 450 BC. It was again suggested by Aristarchus of Samos, but this idea did not catch on. About 1800 years later, around AD ...


15

I doubt that many Babylonians or Greeks or any others who cared about such things ever thought Hesperus and Phosphorus were different objects any more than we think the Morning Star and Evening Star are different. Is there any evidence apart from the use of two names? I think we today underrate what it meant to see the stars clear and bright almost every ...


14

You can read Kepler's Harmonia Mundi (there is an abbreviated English translation, but it includes that part.) Kepler was looking for all kinds of numerical relations for many years (most of his life). Most of the relations he found in Harmonia Mundi are accidental and are of no value for modern science. I agree with your friend, that given 6 pairs of ...


13

There is no sharp difference between "no air" and "very little air". That it is "very little" is seen when we observe the Moon with a telescope. An atmosphere creates a visible haze, especially on the edge of the object (because of refraction). Especially well visible it would be during Solar eclipses. So when people started to observe the Moon with ...


13

Who or what attracted Einstein's attention to Mercury, and when? What alerted him to the idea that Mercury's case was different from all those other cases, when a mundane explanation was involved? I know for sure that Henri Poincaré was aware of the problem and of its singularity - had he been in Kelvin's place, he would have added it to the list, and ...


13

Science fiction author Arthur C. Clarke is often credited with the idea of communication satellites. link That was in 1945, long before any artificial satellite had been launched in reality.


12

The principle was known long ago, to the Babylonians and Hellenistic Greeks but the accuracy of prediction depends on the detail of the Lunar motion (the motion of the Sun is relatively simple). Without a precise Lunar theory, it was possible to predict that an eclipse is LIKELY to happen on such and such date and time, but not with a 100% certainty, and the ...


12

First of all, whether the earth is rotating or everything else is rotating around it, is completely irrelevant for the question. This is just the matter of point of view. As seen from the earth, the fixed stars rotate with period day+night. On this background, the Sun describes a circle slowly with period "one year". When one looks closely, one sees that ...


11

I agree that it is amazing and a credit to Kepler's insight into numerical patterns, which is reminiscent of Euler's. It took Kepler extra 12 years to discover the third law after discovering the first two, perhaps exactly because of the comparative scarcity of data points. According to Kepler, after years of searching for additional patterns on March 8 of ...


11

Today, sky coordinates are measured as "Right Ascension" (RA) and declination. These are similar to the angular coordinates we use for the Earth's surface but are measured on the celestial sphere relative to the celestial equator and pole. By using the current sidereal time, it is possible to map the local sky coordinates (ie. a horizontal bearing relative ...


11

There appear to be conflicting accounts of when the Chinese came to view the earth as spherical. Chinese sources might suggest the 11th century, while western sources suggest the 17th century. According to the sinologist Christopher Cullen, the Chinese believed the earth to be flat and square while the heavens were round until the introduction of European ...


10

One theory says, `If you order the "planets" according to either their presumed distance from Earth (assuming the Earth to be the center of the universe) or their period of revolution around the Earth, you arrive at this order: Moon, Mercury, Venus, Sun, Mars, Jupiter, Saturn Now, assign (in reverse order) these planets to the hours of the day: ...


10

The reason is simple. Baiscaly 365 (approximate number of days in a year) is not divisible on 12 (desirable number of months=the number of Zodiac signs). Then it was proposed to have 6 months of 30 days and 6 of 31, alternating. This still was not good because 6 times 30 + 6 times 31 = 366. So one month has to be 1 day shorter. Why it was decided to make ...


10

Yes. According to this, we don't know who it was to explain the phases using a spherical model, though it was before 600 B.C: The first person to correctly explain the phases of the Moon is lost in history. By the time Pythagoras wrote in 600 B.C., the ancient Greeks knew that the Moon is spherical and that it revolves around the Earth. The Greeks ...


10

The idea of vacuum, or void as it was called in antiquity, did not originally come from considerations about air and Earth's atmosphere, but rather from natural philosophic speculations about the nature of Cosmos, which predate discovering the relation between void and air. Presocratic philosophers starting with Thales considered nothing or void ...


9

I agree with the answer of David, but I would like to add few points to it: It is a common misconception that Aristarchus found (or attempted to find) the sizes of Sun and Moon or distances to them. What his surviving book contains is a method of finding the RATIO of the distance to the Sun to the distance to to the Moon. He estimated this ratio (with a ...


9

The Assayer & Redondi's "G3" Michele Camerota's 2008 Complete Dictionary of Scientific Biography entry on Galileo describes this theory in a section entitled "Atomism and the Eucharist": Atomism and the Eucharist. In section 48 of The Assayer (1623), Galileo set forth a theory of knowledge based on a sharp distinction between “objective” and “...


8

This is an ill defined question. It can be interpreted as "Who was the first to TRIED to measure the distance to the Moon", or "Who was the first to give a correct number", and what is counted as correct number. And even this does not define the question precisely. The crucial question: "in what units"? It is relatively easy to measure the distance in ...


8

We can try to find the necessary informations browsing some History of Astronomy books, like : Anton Pannekoek, A History of Astronomy (1961, original ed : 1961) Christopher Linton, From Eudoxus to Einstein A History of Mathematical Astronomy (2004) and the "classical" studies of Otto Neugebauer on ancient science and astronomy, mainly : Otto Neugebauer, ...


8

Firstly, since the theory was sound and the results reproducible, why didn't it catch on? Aristarchus' heliocentric model was not sound and the results were not reproducible. Not only was there an utter lack of compelling evidence for Aristarchus' heliocentric point of view, there was an immense amount of compelling evidence against that point of view ...


8

The driving force behind the Apollo program was leadership in space over the Soviet Union. Kennedy asked Vice President Johnson to investigate whether "we have a chance of beating the Soviets by placing a laboratory in space, or by a trip around the moon, or by a rocket to land on the moon, or by a rocket to go to the moon and back with a man. Is there any ...


8

You do not say what field of mathematics you are working in, and perhaps there are signs of separation there. Overall however, lively interaction between mathematics and physics is alive and well. John Baez has a blog This Week's Finds in Mathematical Physics, that is full of contemporary examples of it, so does Terence Tao. Nature, a leading journal in ...


8

I assume the doubts refer to the commentary on Dialogue Concerning the Two Chief World Systems in The Galileo affair: who was on the side of rationality? on Less Wrong. I do not believe that Galileo's case was as weak as the post suggests. The main objections to heliocentrism and rotating Earth were known since antiquity: the absence of stellar parallax or ...


8

(I started writing this answer from memory, but on a second look at some sources it turns out to answer the question for the statement of a rotating earth rather than that of a spherical earth... but I'll leave it here; hope the other question is still interesting to you.) The most notable statement of a spherical rotating earth, in Indian astronomy, is by ...


8

One such case comes to my mind: Jules Verne's novel Green ray (1882). Jules Verne popularized this rare phenomenon, and it seems that it has not been scientifically studied before. After Jules Verne novel, the green ray has been photographed and explained. See Wikipedia "Green flash" where there is a list of literature (Jules Verne included!).


8

We do not know. First, Syene and Alexandria are not on the same meridian, Alexandria is about 3° to the West, and second, Syene is not on the tropic (where the Sun is straight up on the summer solstice) either, which is another assumption Eratosthenes makes, according to Cleomedes. Our primary source on Eratosthenes's Geographica, where these assumptions ...


8

Ptolemy's argument can be simply explained in plain English. If the distance to stars was comparable to the size of the Earth, the stars would experience a diurnal parallax, that is the visible relative positions of the stars in the sky would change during one night. But this is not observed. By the way, a similar argument will imply that if the Earth is ...


8

"Libration" loosely refers to longitudinal oscillations due to orbital resonances. The tidal lock and the trojans, the only situations that Wikipedia mentions, are just special cases. The existence of resonances does not require one body to revolve around the other, and Jupiter exerts a major pull on the asteroid belt just as a planet would on its moons. ...


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