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.
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. Read more
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.