October 22 - First Recorded Solar Eclipse

Posted on October 22, 2021

Key points

This is an update of my post published on October 22, 2010:

According to Shu Chin (“The Book”), Chinese observers recorded a solar eclipse on this date almost four thousand years ago, on this date in 2137 BC. (?)

Did you notice my question mark? I was surprised that we would know the particular day as well as year of something that happened so long ago. Obviously, Ancient Chinese didn’t use the same calendar system we used today—just as obviously, nobody who lived “Before Christ” or “Before the Common Era” used those sorts of dates!!— so, I figured, someone must have translated an ancient date into a modern one. I wondered if there was any controversy.

Sure enough, I found a reference to the fact that a scholar named Chen came up with the October 22, 2137 BC, date. Another scholar named Liu dated the same item as October 23, 2110 BC. Wikipedia states that the entire claim of the recording of this eclipse is controversial. Maybe that’s why many sources state that the first recorded solar eclipse was in Babylonia, miles away and years later.

Perhaps part of the problem is that ancient observers didn’t know exactly what was happening. When we see references to a sudden, inexplicable darkness or a dragon eating the sun, is that a recording of an eclipse?

What is an eclipse, anyway?

You probably know that a solar eclipse occurs when the Moon gets between the Sun and the Earth, blocking the Sun’s light from those observers who are in the Moon’s shadow.

On rare occasions, a total eclipse occurs, and every bit of the Sun is hidden behind the Moon. During a total eclipse, the Sun’s disc is entirely covered by the black circle that is the Moon, and suddenly the Sun’s much fainter corona shows up all around the black disc. (Normally, we can’t see the corona because the Sun’s bright light washes it out.)

IMPORTANT: It is not safe to watch a solar eclipse directly, just as it isn’t safe to look directly at the Sun at any time. Here is a guide of safe ways to watch an eclipse.

Note that the moon doesn’t cast a very large shadow on the earth, so people living in a swath of land about 155 miles wide (750 km) would be able to see a total eclipse, which lasts about seven minutes.

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