This article explains the momentous discovery of a 4,000-year-old observatory at a site in Shanxi named Taosi. Scholars have increasingly linked this site with Pingyang, the capital city of King Yao.

How did sunrise look to those observing the skies in 2100 BCE? These animations show how an observer would see the sun rising between the pillars (noted in the previous animation) against the backdrop of nearby hills.

The first observation point after the one believed to be used for sighting the moon — and therefore the xiu ("lunar mansions") — shows the winter solstice. This is where the Xia calendar (and the feng shui calendar) start counting. (Keep in mind that if you can note the solstices and equinoxes you can calculate a calendar and cardinal directions — all the basic building-blocks of feng shui.)

Next time you look at a luopan, note the xiu engraved on the outer ring.