Chinese astronomy has twenty-eight lunar lodges, the xiu, dividing the sky along the Moon's path — the same idea as the Arabic mansions and the Indian nakshatras, at roughly the same scale.

Whether the three systems share an origin or arrived at the same answer separately has been argued for two centuries and is not settled. What is clear is why they agree on the number: if you divide the sky by where the Moon is each night, twenty-seven or twenty-eight is the answer the sky gives you, and everybody who tried got it.