Why carve the day the Sun vanished into bone?

That time, that place

China's Shang dynasty, around 1200 BC. Before any great matter, the king divined. A hole was bored into a turtle's underside or an ox's shoulder blade, a heated rod applied, and the bone cracked — and in the shape of the crack, fortune was read.

Why this question

Here a crucial habit appears: they carved not only the question but what actually happened afterward. Question and outcome, side by side. Whether the divination held up was left in the bone.

What was found

Among those records are days when the sky went dark — solar and lunar eclipses. Dates set down three thousand years ago, and modern astronomers calculating backward confirm an eclipse did occur then and there. That has let historians pin hazy stretches of early Chinese history to exact years. Characters carved to tell fortunes now help fix a calendar three millennia later.