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Title: The explanation of eclipses in Greco-Roman antiquity
Authors: Roberto Casazza, Alejandro Gangui

The search of a rational explanation of eclipses pervades the beginnings of philosophical and scientific thought. Within this intellectual frame, the knowledge of the "saros cycle" (a cycle of 18 years, 10 or 11 days and 1/3 of a day that separates two successive sun or moon eclipses of similar features), inherited by the Greeks from the Babylonians, favoured important theoretical developments in the West. The purpose of this paper is to present, briefly and schematically, a) the ancient theorizations on the causes of eclipses, b) the range of predictability of eclipses in Antiquity, c) the warnings -transmitted by some classical writers- to those who want to observe in naked eyes a solar eclipse, and d) the popular beliefs and social practices upon the occurrence of unexpected eclipses in ancient times.

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Totally addicted to eclipses

This week's total solar eclipse will be seen by tens of thousands of people across north-eastern Australia and the South Pacific, many of them seeing it for the first time.
But some people will travel from all over the world to see it for the second, third ... or even 30th time. For these people, a total solar eclipse is an addiction that's hard to break.

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 In ancient times astronomy was astrology.  Religious ceremonies were set  in accordance with  astronomical observation or prediction.  Priests were astronomers.
Eclipses because of their rarity have been considered to be very special phenomena throughout history.
Eclipses were thought to significance or precede famine, prosperity, disease or  war.
Why this connection was made   may be tied to  events  at the very start of civilisation.  The astronomer priest may have used the information of predicted events to  manipulate the very first societies.
Today, most people realise that  the moon is just an orbiting  rock,  and that  eclipses are  just  planetary, albeit strange, dynamics.

Eclipses occur when the Sun, Moon, and Earth just align in space. In a  Solar Eclipse, the Moon passes directly between the Earth and Sun, and the  Moon casts its  shadow onto the Earth.  Therefore, a Solar Eclipse only occurs when there is a  New Moon.
In a Total Solar Eclipse, the moon completely covers the solar disk; in an annular solar eclipse there is sometimes only a narrow rim of sunlight around the Moon.
The reason why we don't have an eclipse every month is because the  moon does not orbit in the same  plane, or apparent angle, as the  Sun;  the two orbital  planes also have to coincide.
Usually there are only  two Solar Eclipses every year.
A Lunar Eclipse is similar to a solar eclipse, except it is the Earth that  passes directly between the Moon and Sun,  and the  Earth casts its  shadow onto the Moon.
The Moon sometimes appears to turn dark red while in the Earths shadow.  This is because the Earth has an atmosphere, which bends sunlight  onto the Moon. The reflected light although dim can still be seen as a red glow.
A Lunar Eclipse usually occurs two weeks (half a lunar orbit)  before or two weeks after a Solar Eclipse. However, it is possible to have a Lunar Eclipse both before and after a Solar Eclipse -  Three eclipses in a row.
A Lunar Eclipse usually lasts  four to five hours from beginning to end.

cycle  number of days  number of synodic months  number of draconic months  number of anomalistic months  number of eclipse years  
fortnight14.770.50.5430.5360.043
month29.5311.0851.0720.085
semester177.1866.5116.4300.511
lunar year354.371213.02212.8611.022
octon1387.944751.00450.3714.004
octaeteris2923.5399107.399106.1008.434
tritos3986.63135146.501144.68111.501
Saros6585.32223241.999238.99218.999
Metonic cycle6939.69235255.021251.85320.021
Inex10,571.95358388.500383.67430.500
exeligmos19,755.96669725.996716.97656.996
Callippic cycle27,758.75940.0081020.0931007.42080.085
Hipparchic cycle126,007.0242674630.5314573.002363.531
Babylonian161,177.9554585922.9995849.413464.999
tetradia214,038.7272487865.5007767.781617.500


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