Questions tagged [astronomy]

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

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Earliest numeric value for helium D3 line

In late 1868, Norman Lockyer discovered the existence of the D3 emission line of helium in the solar spectrum. What was the earliest published example of a numeric value for the wavelength of this ...
WhatRoughBeast's user avatar
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1 answer
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How does Copernicus explain the discrepancy from "On the Revolutions of the Heavenly Spheres" Book 5. chapter 16

In "On the Revolutions of the Heavenly Spheres" Book 5. chapter 16, Copernicus appears to acknowledge a discrepancy between the old Ptolemy observation and the model. Here is a Google ...
d_e's user avatar
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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 ...
Peter Altman's user avatar
3 votes
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Why did it take so long to discover the shape of the Milky Way?

It was not before the early fifties of the last century that the shape of the Milky Way was figured out. Uptill then only other galaxies were known to have certain shapes It's always easier to find ...
Deschele Schilder's user avatar
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Who else measured the circumference of the Earth in the Antiquity?

The first famous measurement of the Earth's circumference was made by Eratosthenes. But he wasn't the only one to carry out this measurement. For instance Posidonius provided the estimate of the ...
usernumber's user avatar
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How was the first parabolic telescope mirror made, and how was it used, and for what kind of telescope was this work done?

This answer to When was the first true Gregorian telescope built? explains: Newtonian uses one concave and one flat mirror (or just one concave). Gregorian uses two concave mirrors, and Cassegrain ...
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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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Were Kepler's Laws of Planetary Motion the first formal definition of an ellipse?

It seems to me that Kepler's Laws necessitate some definition of an ellipse in terms of a coordinate system. I am wondering whether Kepler's Laws mathematically defined what an ellipse is, or if he ...
Clark Merala's user avatar
21 votes
5 answers
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Did Galileo Galilei believe in astrology?

The Wikipedia page on Gallileo Galilei mentions, among other things: His multiple interests included the study of astrology, which at the time was a discipline tied to the studies of mathematics and ...
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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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Martian dust as ferric oxide and Rupert Wildt

Samuel Glasstone, in The Book of Mars (NASA, 1968, p. 109), wrote "In 1934, the German-born astronomer Rupert Wildt suggested that the bright areas on Mars were composed 'of strongly oxidized ...
Leos Ondra's user avatar
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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 ...
uhoh's user avatar
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Could 17th century astronomers in the Netherlands predict solar eclipses a few months in advance?

In the 17th century Netherlands, could the astronomers, or sailors trained in stellar navigation, predict either total or partial (at least 40% obscured) solar eclipses over the the town of Aardenburg ...
Bob516's user avatar
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How did the first astronomers define what a planet is?

What is the origin of the term "planet" and how did astronomers first define the term?
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Greek astronomy vs astrology

I wonder if would be right to say that while most ancient astronomical activities, such as building and improvement of observational structures, had a strong astrological component, the Greek ...
Mikael Jensen's user avatar
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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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Name of Polaris before it became a pole star?

It seems that all stars as bright or brighter than Polaris have names dating to ancient times, including many stars dimmer than Polaris. So what was Polaris called, in any language, before it became ...
dotancohen's user avatar
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Has anyone explored Ptolemy's epicycles as an early form of Fourier analysis?

Whilst researching science in the ancient world, I came across an observation, which unfortunately I did not make a note of, and so cannot credit, that Ptolemy's epicycles were an early form of ...
Mozibur Ullah's user avatar
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157 views

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 ...
J.G.'s user avatar
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What did the ancient Greeks know about the solar system, and how?

I'm aware that it was known to the ancient Greeks that the planets were somehow different from the stars. But in what depth did they know the solar system? In particular, did they know: that the sun ...
Mauro Giliberti's user avatar
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How critical were Tycho Brahe’s accurate observations?

I am speculating about the value of Tycho Brahe’s - for his time - accurate observations and Kepler’s calculations. Might it have been possible for Kepler to formulate his laws based on Ptolemy’s ...
Mikael Jensen's user avatar
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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 ...
GEP's user avatar
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How did Khayyam calculate the year so accurately?

Regarding the Islamic mathematician and astronomer Omar Khayyam, known (among other things) for his accurate calculation of the year, quoted from https://www.famousscientists.org/omar-khayyam/ ...
CaptainCodeman's user avatar
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In which year, people found that sun is not the only star in the universe? [duplicate]

It is a well-known fact now that the sun is one of the multiple stars in the universe. But in which year people at least hypothesized the fact that we are living in a universe with multiple stars?
hanugm's user avatar
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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 ...
Cleonis's user avatar
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Was Herschel ever inspired to write music through his astronomy research?

While it is known that William Herschel was both a composer and an astronomer, could it be that he ever wrote music based on astronomy, or how he felt his research was proceeding? Just as Beethoven ...
Nachiket Kulkarni's user avatar
1 vote
1 answer
179 views

What astronomy efforts required multiplication of large numbers around 1600?

I'm reading an article about the history of logarithms and it says: One problem that was plaguing people at the time, especially astronomers, was arithmetic. Astronomical calculations required the ...
Jon's user avatar
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How large were the differences in the orbit of Uranus which led to the calculation of the existence of Neptune?

After Uranus was discovered and its orbit calculated, its future orbit was calculated, and its future positions as seen from Earth were calculated. And observers of Uranus began to notice that Uranus ...
M.A. Golding's user avatar
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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'...
Nikola Ubavić's user avatar
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How did the initial scientists conclude the new moon phase is not an eclipse?

My apologies if this is too naive a question. I keep wondering what steered people away from assuming the new moon to be an eclipse and hence go on to figure the angular difference in the orbital ...
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Laplace's Treatise of celestial mechanics

I am interested in nineteenth-century astronomy and Laplace's Treatise of celestial mechanics is often mentioned as one of the most significant contributions to science in this period. The more than ...
poset's user avatar
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6 votes
1 answer
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Were epicycloids from astronomy acceptable curves in Greek geometry?

My simplified historical understanding is as follows. Euclidean geometry accepted a limited number of geometrical objects (straight-edge and compass constructions, conics). Descartes' Géométrie ...
sqrt_eric's user avatar
5 votes
1 answer
651 views

Did Ptolemy and other Greek scientists actually measure the distance to the Sun?

According to Subhash C. Kak: Early Theories on the Distance to the Sun: “Pancavimsa Brahmana states that the heavens are 1000 earth diameters, de, away from the earth. The sun was also taken to be ...
Mikael Jensen's user avatar
3 votes
0 answers
80 views

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 ...
user35915's user avatar
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1 vote
3 answers
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What made Newton realize that the law of gravitation was 'universal'? [duplicate]

Newton's law of gravitation operative near the earth is the same law causes the earth and the other planets to go around the sun and other heavenly phenomena. Was it a giant leap of faith by Newton or ...
Solidification's user avatar
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0 answers
42 views

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?
Geremia's user avatar
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What is the historical basis for the length of a sidereal year?

It is understandable that the length of a solar year can be found out using the time of solstices. But how did they find the length of a year with respect to the stars?
Arnab Chowdhury's user avatar
3 votes
0 answers
91 views

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 ...
timur's user avatar
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39 votes
2 answers
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Why do we call Tycho Brahe by his first name?

Why do we use the fist name in Tychonic system or Tycho's comet of 1577, instead of using the last name of Tycho Brahe? For comparison, we have the Ptolemaic system and the Copernican system. I am ...
timur's user avatar
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7 votes
2 answers
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Who first reported the Crab pulsar's pulsing but was dismissed by an astronomer?

This answer to Has great eyesight been necessary for astronomers? mentions Astronomer Jocelyn Bell Burnell's recounting of a likely first visual observation of a pulsar. This can be found for example ...
uhoh's user avatar
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3 votes
2 answers
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Historical mentions (as if fact) that Sun never rises or sets

Now-a-days it is well known that sun never rise or set but appears to human The sun stays in its position at the center of our solar system. It doesn't rise and set. But it appears to rise and ...
hanugm's user avatar
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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).
Leos Ondra's user avatar
4 votes
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What were the applications of conic sections before Kepler?

When recently asked for a practical application of parabolas, I responded by talking about objects in free-fall. Afterwards as I was re-thinking this conversation it occurred to me that an object in ...
Chaim's user avatar
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0 answers
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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 [...
emi's user avatar
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0 answers
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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 ...
Display Name's user avatar
7 votes
1 answer
340 views

What was the "libration of Pallas" that Gauss studied, when Pallas is not a moon of Jupiter?

This question is a request for general explanation of an astronomical phenomenon known as "Pallas libration", and isn't much about the details of Gauss's mathematical model of this ...
user2554's user avatar
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2 votes
0 answers
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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 ...
DDS's user avatar
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0 votes
3 answers
249 views

Does Heliocentrism predate Copernicus?

I have seen this mentioned on the interwebs a few times. people have mentioned that some Greek thinkers and Islamic astronomers came up with heliocentrism before Copernicus and that Copernicus copied ...
user4281's user avatar
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3 votes
1 answer
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Several questions about Gauss's contributions to observational astronomy

I just want to check if anyone has additional information about a private astronomical research begun by Gauss in 1819, which dealt with the "movements of the solar system" in the galaxy (motion of ...
user2554's user avatar
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1 vote
2 answers
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Who were the other European astronomers who identified new stars around the time of Tycho Brahe?

Wikipedia notes: Early European astronomers such as Tycho Brahe identified new stars in the night sky (later termed novae), suggesting that the heavens were not immutable. Who were the other ...
Frank Hubeny's user avatar