Questions tagged [archaeoastronomy]

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Earth's and Sun's rotation in the Ptolemaic world

In Ptolemy's geocentric model the Sun travels through the ecliptic and around the Earth once every 24 hours and the Earth does not rotate about its axis. What is Ptolemy referring to when he talks ...
Adrien Hingert's user avatar
1 vote
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Understanding Ptolemy's Almagest

This is an extract from page 138 of Ptolemy's Almagest (Toomer): [Hipparchus] made a very accurate observation of the autumnal equinox, and says that he calculated that it occurred at midnight, third-...
Adrien Hingert's user avatar
1 vote
1 answer
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Ancient parallax

When ancient Greeks could not observe any parallax, what were the two bodies they were looking at to determine this? I imagine the stars (or a specific star) would have been one of these, but what was ...
Adrien Hingert's user avatar
6 votes
1 answer
1k views

Could ancient astronomers have proven heliocentrism?

Could ancient astronomers have proven heliocentrism and, if so, how could they have done so?
Adrien Hingert's user avatar
2 votes
1 answer
131 views

Did the Ptolemaic system have rotating center of the deferent for Venus?

I've come across this diagram of the Ptolemaic model. Am I understanding correctly that this means that all the planets' deferents rotate around a point which next to Earth, while Venus' deferent ...
Adrien Hingert's user avatar
1 vote
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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.
Adrien Hingert's user avatar
2 votes
2 answers
301 views

How did the ancients determine the exact time of equinoxes and solstices?

Hipparchus seems to have known that 94.5 days passed from the winter solstice to vernal equinox. How did he measure this? Equinoxes and solstices don't happen only at noon when the Sun is highest, but ...
Adrien Hingert's user avatar
3 votes
1 answer
181 views

How did Hipparchus measure the length of the tropical year?

My understanding is that he counted the number of days between every other equinox. The first year he would have counted 365 days, but after 4 years the tally would have reached 1461 days. Dividing ...
Adrien Hingert's user avatar
29 votes
2 answers
7k views

How did Eratosthenes know the Sun was very far away?

Eratosthenes calculated the radius of the Earth from the difference of the lengths of shadows between Aswan and Alexandria were different (see also here). But this could also happen if the Earth were ...
Rohit Pandey's user avatar
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Astrologer's view of the planets' position

Assuming there was a standard for (early) astrological calculations, did the astrologers have a 2- or 3-D view of the planets' position?
Mikael Jensen's user avatar
3 votes
1 answer
189 views

Is it possible to narrow down possible dates for the following eclipse pattern?

I am searching for an year which satisfies the following criteria. Dates are in Gregorian calendar. Criteria Year range 3800 BC to 500 BC Solar Eclipse of any kind between October 14 and October 22 ...
Profile name's user avatar
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1 answer
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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
3 votes
2 answers
666 views

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
1 vote
1 answer
208 views

When and how was it discovered that the sun was in different positions depending upon longitude?

It seems to me that the ancient Greeks knew that geographic location affected the apparent position of the sun in sky but given the lack of rapid travel or communications or reliable clocks, how was ...
releseabe's user avatar
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1 vote
1 answer
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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
5 votes
1 answer
106 views

Spirals as calendrical representations

A recent work proposed that the double spiral motif found at Newgrange (ca. 3200 BC) is a calendrical representation. Looking south the northern peoples observed that the arc traced by the sun widens ...
sand1's user avatar
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1 vote
1 answer
171 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?
Partha Shakkottai's user avatar
3 votes
5 answers
454 views

How did ancients differenciate between inner and outer planets?

It seems to me that ancients (greeks at least) knew that in their geocentric model Venus and Mercury were closer to them than the sun, and correctly differenciated inner (Mercury and Venus) from outer ...
user3301482's user avatar
3 votes
1 answer
574 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 ...
Ben Storey's user avatar
2 votes
2 answers
2k views

How did Ptolemy calculate the distance to the Moon?

I've read somewhere that Hipparchus measured the distance to the Moon using the lunar and solar eclipse and obtained a value of around 67.3 Earth radii. It also says that soon after Ptolemy gave a ...
cal's user avatar
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4 votes
1 answer
188 views

When and why did the 'spiky star' appear as an image in art and science?

Telescope images of stars look like crosses, although they are point sources of light. Featureless dots. Diffraction along the vanes of the support structure that holds up their secondary mirror is ...
LocalFluff's user avatar
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What is the remarkable configuration of directions at 51° N?

A 2015 document from Stanford Solar Centre informs us that Stonehenge, The Goseck Circle and Majorville Medicine Wheel are on the same latitude (51° N.) with the Newgrange monument slightly to the ...
sand1's user avatar
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2 votes
2 answers
426 views

Length of the year in Aztec/Maya calendar

In an old book of Prescott (died in 1859), The conquest of Mexico, the author described Aztec calendar with a year of 365 days. To compensate for the difference, every 52 years an additional 12.5 days ...
Alexandre Eremenko's user avatar
3 votes
1 answer
403 views

What role did meteors and comets play in early astronomy?

Apart from the location, brightness and color of the stars themselves, astronomy obviously originated from an interest in transient phenomena against the fixed but rotating star sky. The rise and set ...
LocalFluff's user avatar
7 votes
2 answers
388 views

Did Archimedes know about Callipus?

Various sources, such as Cicero's Republic state that Archimedes had made a machine consisting of glass spheres that represented the Eudoxian system of the world. Considering that Callipus died over ...
Michal Paszkiewicz's user avatar
4 votes
5 answers
1k views

Why did the ancients believe celestial matter was of a different type than terrestrial matter?

Why did the ancients believe celestial matter is of a totally different type than terrestrial matter? From a footnote in Christopher A. Decaen's The Thomist 68 (2004): 375-429 article "Aristotle's ...
Geremia's user avatar
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20 votes
2 answers
13k views

Origin of 360 degrees?

This is by far one of the most challenging and popular HSM questions on the Net. Proofs are, countless discussions about it in math forums. The answers only led to two theories, which Wikipedia does a ...
M.A.R.'s user avatar
  • 345
26 votes
6 answers
9k views

Is there an astronomical reason behind the order for the names of days of the week?

The seven days of the week seems to be commonly named after celestial bodies. What I find curious is that all seven days apparently share the same names in both West and East. Sunday is, of course, ...
Semaphore's user avatar
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