Questions tagged [astronomy]
The study of celestial objects and phenomena outside of the Earth's atmosphere.
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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?
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71 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 ...
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1answer
5k views
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 ...
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1answer
86 views
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 ...
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2answers
160 views
Mention of the fact 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 ...
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44 views
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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2answers
169 views
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 ...
2
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0answers
77 views
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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35 views
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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1answer
174 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 libration. As is ...
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0answers
64 views
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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3answers
98 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 ...
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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 ...
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2answers
81 views
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 ...
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2answers
101 views
How has the estimate of the number of stars in the universe changed over time?
Current estimates for the number of stars in the universe are about 10^22. However, that number has changed several times as new observations have come forth. How has the estimate of the number of ...
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0answers
86 views
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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1answer
98 views
Did knowledge of astronomy spread among Indo-European civilizations in antiquity?
Early civilizations of india, Greece, Babylon, China and Egypt have progressed in astronomy. Is there any shared knowledge among them and if any how can we find out?
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145 views
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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2answers
473 views
Where did Ptolemy compare the Earth to the distance of fixed stars?
I read the following in C. S. Lewis, Miracles (page 77-8)
The immensity of the universe is not a recent discovery. More than seventeen hundred years ago Ptolemy taught that in relation to the ...
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1answer
77 views
Apparent contradiction in Copernicus' Commentariolus
There seems to be a contradiction in the assumptions that Copernicus makes when attempting to explain the motion of the planets:
http://dbanach.com/copernicus-commentarilous.htm
Assumptions 1 and 3 ...
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54 views
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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1answer
63 views
Where to find some early discussions of the Equinox(es)?
Said quickly, solstices are rather perceptible while the equinox is a mental construction. Archeoastronomical evidence shows that neolithic people already had knowledge about the solsticial points on ...
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101 views
What calculation did Halley or anyone else do to estimate the effects of Jupiter and Saturn on Halley's comet's return in 1758/9?
This answer to the question First observation that the movement of a planet or asteroid in its orbit was affected by another planet says:
In 1705, with the mathematical assistance of Issac Newton, ...
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30 views
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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1answer
233 views
How did Eratosthenes determine that Alexandria and Syene were on the same meridian?
As discussed over here, Eratosthenes measured the earth’s circumference by comparing shadows cast at apparent noon at two locations separated by a known distance.
Although accounts of the event (like ...
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82 views
What's the relationship between Aristotle's theory of elements and motion and geometry?
I'm having a hard time gathering my thoughts about this.
I'm trying to find a connection or some sort of relation between the first 3 axioms (postulates) of Euclidean geometry (though around Aristotle'...
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2answers
200 views
Was Newton's successful calculation of precession of equinoxes a fluke?
I have looked at several sources, and Newton was right about the fact that the Earth is not a perfect sphere, but an ellipsoid caused the precession of equinoxes, as the Moon's gravitational ...
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1answer
70 views
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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1answer
59 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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1answer
174 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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1answer
866 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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2answers
130 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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101 views
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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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
116 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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1answer
469 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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2answers
234 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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1answer
58 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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0answers
82 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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657 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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1answer
90 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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1answer
100 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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2answers
554 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
286 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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2answers
777 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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1answer
95 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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1k 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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2answers
196 views
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
149 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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124 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 ...
