Questions tagged [astronomy]

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

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How did Hertzsprung-Russell diagrams end up so confusing?

HR diagrams show in which of several sequences individual stars fall, each respecting the rough principle that hotter stars are of higher luminosity. (Sequences other than the main sequence may bend ...
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Notable theories on the far side of the moon pre 1959

On October 7th 1959, the soviet Luna 3 probe took the first picture of the far side of the moon. It has been known since ancient times that the moon was a sphere. It would have doubtless been ...
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How did Cassini measure the "Cassini state" of the Moon? What measurements were made; what did the data look like?

The Phys.org article Physicists provide first model of moon's rotational dynamics, accounting for the solid inner core describes the September 2018 paper by Christopher Stys and Mathieu Dumberry The ...
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Width of zodiac

Why is conventional width of zodiac set to 16 degrees (8 degrees at both sides of ecliptic), see for example this Taurus plate from Bayer's Uranometria? I assume that the planet which defines the ...
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Did a boat full of Louis XIV's Jesuits and some Siamese dignitaries plan on seeing a solar eclipse on May 17, 1687

The interesting Cosmic Elk article Eclipses in Siam (now Thailand) History and Legends says: While the Siamese ambassadors and their entourage were visiting ship yards and armouries and making ...
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Literature on Mayan mathematics

I asked this question on math.se and they sent me here. It is well known that Mayan people used vigesimal (base 20) numeral system, and had had an advanced calendar system. Except for these facts, I'...
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Historical accounts of a oft-cited quip by astronomer Walter Baade

I am looking for any documented, historical reference to an oft-cited humorous reply by German astronomer Walter Baade (1893 – 1960). After having asked if other astronomers were familliar with the ...
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Was the width of the Atlantic first determined in 1584?

In Eclipse: Journeys to the Dark Side of the Moon by Frank Close, it is stated that the 1584 lunar eclipse was used to determine the width of the Atlantic, by measuring the times in London and in ...
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What happened to the data from the survey that discovered the first pulsars?

The first pulsars, starting with B1919+21, were discovered in the late 1960s in data from the Interplanetary Scintillation Array at Cambridge. The data from the telescope was recorded on paper by four ...
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How did the Astronomical model of Sacrobosco differ from Ptolemy's?

According to Wikipedia, Sacrobosco's De Sphaera described the Ptolemaic system, but drew on additional ideas from Islamic Astronomy. How did Sacrobosco's model differ from that of Ptolemy?
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When did we have first calculations of moon phases?

I'm interested in knowing more about the history around lunar tables and calculation of moon phases. When did we have first (reliable) calculations of moon phases and first (reliable) lunar tables? ...
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History of: Galaxy rotation rate estimates

Out of sheer curiosity: When was the first discovery/estimate of the rotation rate of our Galaxy? (To my understanding: in astronomy the angular velocity of the Solar System with respect to the Milky ...
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Thomas Kuhn and the Relationship between Astronomy and Cosmology

In The Copernican Revolution, Thomas Kuhn states that "...only the Western civilizations which descend from Hellenic Greece have paid much attention to the appearance of the heavens in arriving at [...
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On Trigonometric Methods Available to Aristarchus

Approximately 2300 years ago, Aristarchus proposed a method for determining the relative distances of the sun and the moon in relation to the earth. Specifically, he asserted that when the moon is in ...
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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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Before the IAU, what was the international governing body for naming astronomical bodies?

Today, the commonly recognized authority on the naming of astronomical bodies is the International Astronomical Union (IAU). It was created in 1919, and quickly rose to a position of prominence within ...
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Determining the temperature of a remote star by using the black body radiation formula

I am new to astrophysics. There is a question about the celebrated Harvard classification. Can people at 1900 determine the temperature of a remote star using the black body radiation formula? I ...
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Was Kepler aware of the following golden relationship between the planets?

Was Kepler aware that Venus and Mars have a golden section relationship other than that he attributed to them in his 5 perfect solids model of the Solar System? The dodecahedron and the icosahedron, ...
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Were ancient astronomers (Babylonians, Egyptians or Greeks) aware of the solar analemma?

Is there any proof or even just indication that they did: I can't find anything online and was hoping for some help.
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Can "Laplace limit" phenomenon be considered the first example of non-convergent Fourier series?

Traditionally, the first example of a non-convergent Fourier series of a function is considered to be the example constructed in 1870 by the mathematician Paul David Gustav du Bois-Reymond. His ...
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Tycho Brahe and the distance to the fixed stars

How far away did Tycho Brahe estimate that the fixed stars were? In multiples of our sun I imagine!
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Where did Wm. Herschel plan to put their head? Peer over the edge of the famous 40-foot telescope or try to get less off-axis; closer to the center?

From here: click for larger Herschel's 40 foot telescope had a diameter of 48 inches (122 cm) and was f/10. It was not a good mirror (cast in metal) and apparently not used that much. But my ...
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Historical proofs of the series expression for the Bessel function of the first kind

Introduction The Bessel function of the first kind $J_n(x)$ ($n \in \mathbb{Z},\ x \in \mathbb{R}$) appeared early among other topics, in Celestial Mechanics, in the series expression of the true ...
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When was the first quarter first used for moon phase?

For this doesn't make sense - we see one half of moon, not one quarter (at least compared to full moon).
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When did the research field of Astrophysics begin?

I have this vague idea that Astrophysics morphed out of Astronomy as a field of study and research. I am curious if this is true and when did Astrophysics become separate from Astronomy as a field of ...
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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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English translation of Parisian Alfonsine tables (the 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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At what point did Einstein realise that gravity was curvature of spacetime?

Did he realise this as soon as he thought of light curving due to gravity or was this something that took him a while to realise?
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What is the origin of Zodiac (Kaalachakra) signs?

I think that The Zodiacal signs are of Vedic origin. Hindus, Greeks and Sumerians all have Zodiacal signs. Which is the most likely origin? The middle ring is the zodiac in the same between India and ...
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Is there any book dealing with the history of both astronomy and geometry?

I am preparing an introductory course on the history of astronomy and geometry for intermediate students. The intention is to teach Copernican heliocentrism, Kepler's laws of planetary motion & ...
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Is it true that there were "wooden guiding structures" proposed, by the ancient Greek, to account for the motions of the planets?

I can remember after attending a philosophy of science class, I put forward the thought ancient Greek had about the motion of the planets. I had read about them thinking there are wooden circular ...
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When was the surface temperature of the Sun first measured?

William Herschel thought that the Sun was inhabited as did others at that time. Presumably there was no knowledge of its surface temperature, so when was it first realised that the surface was far ...
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In which year the notion of star death started?

In which year, does the fact: every star will ultimately die came in to existence?
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Who was the first to state that scientific theories could be used to make predictions?

It seems to me that very few if any scientists/philosophers stated that science could be used for predictions before the early 1900s. In the scientific context I have only encountered the use of the ...
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Did pre-Galilean astronomy inspire Mach's principle?

Was Mach, in his formulation of "Mach's principle," influenced by pre-Galilean astronomy, such as that of Aristotle in On the Heavens, where heavenly bodies influence terrestrial ones?
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How were sundials first divided up into hour-long segments?

Even with present-day knowledge of celestial mechanics, if you asked me to go outside and set up a sundial without the aid of any other timekeeping devices, I would have a very hard time. The time ...
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How did Kepler know that orbits are elliptical?

Suppose I was living in his time. How would Kepler explain that the orbits are elliptical? Since none of his 3 laws explain why orbits are elliptical, I assume he must have had other reasons to ...
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