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Questions tagged [astronomy]

The study of celestial objects and phenomena outside of the Earth's atmosphere.

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Who correctly first explained the reason why you can see certain constellations only in certain seasons?

Of course, only heliocentric model can explain this. But, was this Copernicus himself or Galilei?
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39 views

Precision of Ancient/Medieval Astronomy (wrt Eclipses)

Today we can predict lunar/solar eclipses down to the precision of seconds.[1] But what was the precision like in medieval times? I imagine it must have improved over centuries. To keep the question ...
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107 views

Who first solved the two-body problem in 3D?

Who first solved the two-body problem in 3-dimensions? Was it Laplace?
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115 views

Sphericity of Earth from lunar eclipses - is Aristotle's argument valid?

Aristotle is often credited with proving the sphericity of Earth from the fact that the shadow of the Earth on the moon during lunar eclipses is always an arc of a round circle (as opposed to arcs of ...
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113 views

Who was the first to understand the concept of outer-space?

Who first understood that celestial bodies (stars, planets, and moons) are moving in a 3D space and not points of light moving on Earth's dome? Also, when and how did they realize that celestial ...
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Was Captain Cook’s voyage to observe the transit of Venus going to enable better ship navigation at the time?

On a recent visit to the Royal Observatory at Greenwich I was struck by its proximity to the Naval Academy next door. The theme of the history of clocks and development of astronomy was driven by the ...
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375 views

Has science fiction ever caused scientists to do real research?

Has science fiction ever caused scientists to do real research? Science fiction here means fiction that tries to explain things in the world rather than speculate about the future or unexplorable ...
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1answer
75 views

Do astronomers still use decimal time?

Wikipedia states that decimal time - where the time of the day is expressed as a decimal part of the day - "have been used by astronomers ever since [Laplace introduced them]". An example by Herschel ...
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123 views

Did Indian astronomers realize the sphericity of the earth independently of the Greeks?

Reading Wikipedia's articles on the flat earth, spherical earth, and history of geodesy makes it clear that virtually every society recognizing the spheroidal shape of the earth today owes the ...
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76 views

When did spring-driven clocks start being used?

On a tour of the Royal Observatory at Greenwich I saw the following display on the history of mechanical clocks: They suggest that mechanical clocks and astronomy weren’t really combined in England ...
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39 views

When did mechanical tower clocks start being used?

On a tour of the Royal Observatory at Greenwich I saw the following display on the history of mechanical clocks: The suggest that mechanical clocks and astronomy weren’t really combined in England ...
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68 views

Historical development of role of astrology in medicine?

The OED defines "iatromathematics" as Practising medicine in conjunction with astrology. Pre-17th century, it seems most scientists (physicians included) believed in the influence of the stars on ...
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253 views

How scientifically valid were Galileo's heliocentric arguments?

As far as I know, while Galileo's hypothesis about the tides was wrong, his discovery of the phases of Venus while passing the sun should have been sufficient to leave the geocentric crystal spheres ...
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76 views

Did Galileo really see Galilean Moons?

I want the answer to incorporate apparent magnitudes of those moons, power of his telescope, light pollution of that time, successful recreation of the scenario of watching Galilean moons using that ...
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55 views

Who coined the term “degenerate star”?

I'm trying to find a good source for the definition of degenerate matter to differentiate it from Fermi gases. For my research a good section on history would be nice. This question is more ...
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178 views

What astronomical reason led to the creation of the trigonometric sine and cosine?

Sines and cosines are commonly introduced as ratios of sides of a triangle with its hypotenuse and attributed to ancient Indian scholars. However, I've never actually thought of the reason for ...
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1answer
96 views

Did the Mayan's really predict the solar eclipse?

The Mayan's astronomical observations were outstanding given the tools they had, and investigations of the Dresden codex published by Harvey and Victoria Bricker in 1983 predicted the July 11th, 1991 ...
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300 views

How did Ptolemy calculate the distance to the moon

I've read that Hipparchus measured the distance to the Moon using the lunar and solar eclipse and obtained a value around 67.3 Earth radii. It also says that soon after Ptolemy gave a more accurate ...
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80 views

What was the impact on science and philosophy of the discovery that the Milkyway is not the whole Universe?

I can think of no discovery bigger in terms of correction of a belief if the metric is, How much bigger is something really than believed? Of course that is not the only significance. It is a major ...
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386 views

Why was China slow to recognise the sphericity of Earth?

Wikipedia notes that, while knowledge Earth is approximately spherical was obtained in ancient Greece, and became standard among educated people in Europe and the Middle East long before 1300 AD, ...
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Why is an inch (in the English Imperial system of measure) as long as it is?

My question is about the length of the inch which is a subunit of the Imperial foot. Is there any connection whatsoever between the Imperial system for units of measure and the dimensions of the ...
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1answer
127 views

When did astronomy first discover that the stars are bigger than the moon?

We take it for granted these days that the stars are unimaginably bigger than the planets and the moons. But when you look at the sky, it does not appear this way. The moon looks bigger and brighter ...
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101 views

Kepler's genius, How?

I have a very simple question. How Kepler knew that orbits are elliptical, say I was living in his time. How would Kepler explain that the orbits are elliptical (since none of his 3 laws explain why ...
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3answers
105 views

Why was in 1584 the eclipse of the moon used to calculate the width of the Atlantic ocean rather than just using the Sun itself?

In this video is explained that in November 1584 the width of the Atlantic ocean was discovered by comparing the hour when the eclipse of the moon started in England with the hour when the eclipse ...
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How was stellar parallax tested by Tycho Brahe?

Explanations of stellar parallax that I have found involve examining the apparent motion of a nearer star relative to a background of more distant stars, as the Earth moves around the sun or as the ...
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120 views

Is it known where Eratosthenes first heard of the “well of Syene”?

The American Physical Society's This Month in Physics History; June, ca. 240 B.C. Eratosthenes Measures the Earth says: Eratosthenes had heard from travelers about a well in Syene (now Aswan, Egypt)...
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Were people in the ancient or medieval times aware of how exactly a solar year is equal to a lunar year?

Was it common knowledge around 600 AD or perhaps 30 BCE that 200 solar years for example were equal to 209 lunar years? In which period of history precisely can we say that such a thing was confirmed?
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58 views

Kepler's position with respect to Tycho Brahe's world system?

When Kepler was an assistant of Tycho Brahe, did Kepler in public declare his support for Copernicus' system or Brahe's system (the earth at rest, but the planets orbiting the sun) or was he undecided?...
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106 views

Is there any evidence supporting this claim about Cassini and his ovals?

The Wikipedia article for Cassini ovals claims in the introduction that "Cassini believed that the Sun traveled around the Earth on one of these ovals, with the Earth at one focus of the oval." This ...
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2answers
92 views

Where are the mirrors of the historic telescopes today?

Are the great mirrors and lenses of historic telescopes preserved? Those of Herschel and Rosse and many others and back to the 18th and 17th centuries. The wooden structures of those telescopes I can ...
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4answers
543 views

Historical knowledge of Distance of Earth from Sun

I asked the following question on the Physics stackexchange, only to be notified that it was more suitable for this forum. The link to original post can be found at: https://physics.stackexchange.com/...
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123 views

Determination of planetary mass and radius

At the beginning,how and using which principles scientists determined the mass and distance from sun of various planets?
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2answers
105 views

Was an expanding universe proposed before Edwin Hubble's observations?

General relativity (1915), as I've heard it explained, describes a universe that is either shrinking or expanding. By adding a cosmological constant it can describe a universe in eternal steady state, ...
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1answer
190 views

Did Isaac Newton make astronomical observations?

What role did astronomy play for Isaac Newton? He was a good friend with Edmond Halley the astronomer. Kepler's laws were obviously the foundation for his physics. And he revolutionized optics too, ...
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87 views

How and when did the Titius-Bode rule first become known as a “law”?

The Titius-Bode rule's fit to the solar system was a bit clunky at best, and it was not really testable in its day. It could not have been used to predict something else, and then that prediction ...
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266 views

How important was the prediction of Neptune in 1846 for the Oxford evolution debate?

The short story is that based on Kepler's and Newton's physics, in 1846 Le Verrier mathematically predicted the existence and current location of Neptune within a single angular degree, and it was ...
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57 views

What can be inferred about the eyesight of early astronomers from their recorded observations?

The journals kept by the likes of Galileo, Kepler and Herschel provide details about what objects they discovered and what kinds of optical instruments they used to discover them. Taken together, ...
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Did Kepler arrive at his planetary laws based on Mars's orbit alone?

Kepler apparently arrived at his first two laws based on the Tycho's data for Mars. But Mars has the largest eccentricity except for Mercury, so it is easier to tell the difference between a circle ...
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When William Herschel discovered Uranus, who else at the time had a comparable telescope?

William Herschel built a big telescope and observed Uranus in 1781. I'm trying to figure out who else had a comparable telescope at the time, who could verify these observations? Apparently Johan ...
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English translation of Parisian Alfonsine tables (1400s)?

I'm interested in an English translation of the Alfonsine tables published in Paris in the 1400s. I know there is an English translation of what survived of earlier Alfonsine tables from Castile, but ...
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1answer
429 views

When was it discovered that the Earth wasn't round?

We know the Earth isn't a sphere: that is, the equatorial circumference isn't equal to the polar circumference. When (and how) was this discovered? I can put a lower bound of around the 3rd century ...
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783 views

When was the mechanism behind seasons on Earth discovered

When was the mechanism behind seasons on Earth discovered? I'm talking about the angle between the Earth's rotational axis and its orbital axis. I read on Wikipedia here that Earth's obliquity ...
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1answer
35 views

When did the Bayer designation Gamma Sagittarii become Gamma1 & Gamma2 Sagittarii?

Some authors talk about Gamma Sagittarii as a single star, while others use Gamma1 Sgr for W Sgr and Gamma2 Sgr for 10 Sgr (Gamma Sgr being then ambiguous). SIMBAD database uses Gamma1/Gamma2 as of ...
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2k views

Did the ancient Chinese know the earth is a sphere?

The ancient Greeks knew this fact. How about the chinese? If not, when did they realize that the earth is a sphere? By themselves or from other people?
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1answer
140 views

How did the Arabs determine the longitudes of cities?

I am reading the book by Berggren, 'Episodes in the mathematics of medieval islam'. An important problem is determing the direction of Mecca with respect to a local city. The book introduced a method ...
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242 views

What is Galileo's opinion of Kepler's work?

They are contemporaries. Keper lives from 1571 to 1630, and Galileo lives from 1564 to 1642. The former's life span is contained in that of the latter. So, did Galileo hear of Kepler's work and give ...
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1answer
197 views

How did Kepler make his discovery?

It is often said that he used Tycho's data. But the apparent motion of a planet is chaotic, right? The reason is simply that we are living on and observing from the earth, but not the sun. So, how ...
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193 views

Did Bruns establish that the 3 body problem has no non-trivial conservation laws?

I'm reading Colin Pask's book Magnificent Principia and in 16.7.2 he states that the difficulty of the 3 body problem is in part tied to the lack of additional conservation laws at our disposal. In ...
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141 views

When did the estimates of planetary distances made between Ptolemy and Copernicus produce the pattern suggesting heliocentrism?

Two patterns in the structure of the Ptolemaic model make the transformation of coordinates to the Copernican model seem "natural" to modern eyes: the alignment of the radii of the (second) ...
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355 views

Hidden agenda of the Galileo trial?

Redondi argued that Galileo's trial on heliocentrism was merely a show trial concealing the real objection against Galileo among the catholic establishment, which was his atomism thought to be at ...