July 17 - Total Solar Eclipse in China

  Posted on July 17, 2022     

This is an update of my post published on July 17, 2011:

The earliest record of a confirmed total solar eclipse happened on this date in 790 B.C. The record was written in China. The reason we can confirm the date, although we don't have any records of the event from any other civilization, is because knowledge of the movements of the sun and the moon allow us to compute eclipses of the past as well as predict eclipses of the future!

Historians give the ancient Chinese credit for being the most accurate observers of astronomical events in the world, before the medieval Islamic or Arab astronomers eclipsed them. 

(Yeah, I used the word eclipse to mean “surpass” or “outshine” in an article about astronomical eclipses!)

One of the main reasons for all this careful observation was timekeeping. The Chinese used a lunisolar calendar which indicated both the lunar phases and the position in the solar year, with the four seasons depending on day length. Because lunar phases and the solar year are independent, the Chinese had to add leap days in order to keep the seasons in sync with the calendar—and so a lot of time was spent keeping tabs on constellations and the sun and moon.

Some ancient Chinese scholars conceived of the heavens as a dome-like hemisphere or as a celestial sphere like the one conceived by ancient Greeks. However, one school of ancient Chinese astronomers (the Xuan Ye school) viewed the heavens as an infinite space with stars and other bodies floating about “at rare intervals” (in other words, far from one another),  and that each celestial body had independent speed and movement. In other words, these Chinese cosmologists thought of the celestial bodies as being not attached to anything. 

The Xuan Ye view is very close to the theories of modern astrophysicists!

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