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Questions tagged [equinox]

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Solar azimuth for celtic fire festivals

I am pretty new to astronomy, and I have fallen down rabbit hole creating a new Metonic calendar in Javascript. As part of this I would like to calculate when the sun is half way between a solstice ...
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Are the stars seen at the equator different throughout the year?

If you live on the equator and look up at the night's sky at, say, midnight, would you see a completely different sky on the 1st of January than you would on the 1st of July? I assume you would as ...
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What is the great (platonic?) year? How could it be explained in laymen's terms?

How could a great year be explained in laymen's terms? According to the definition in NASA's Aerospace Dictionary it is a complete cycle of the equinoxes around the ecliptic that completes in 26000 ...
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Why is the time between equinoxes different?

The path of the Earth around the sun is described as being an ellipse, with the Sun being at one of the foci of the ellipse. Since an ellipse, by definition, is symmetrical with respect to the foci, ...
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What's a good model for the vernal equinox year? Can it increase forever?

Duncan Steel (2002) makes an interesting argument that the notion of year is (1) somewhat arbitrary and, more interestingly (2) one notion of year can increase while another decreases. His examples ...
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How was the time of equinox measured in ancient times?

In the book "The Crime of Claudius Ptolemy" by Robert Newton, on page 81, it reads as follows: When we measure the time of a solstice, we measure the time when the meridian elevation angle of the ...