The Big Dipper Time Keeping Function of a Composite Jade Ritual Artifact from the Late Hongshan Culture

This study employed morphological measurement, astronomical retro‑simulation, and XRF non‑destructive testing to systematically analyze its structure, craftsmanship, and material characteristics. The artifact uses natural mineral veins and a carved sightline as references and is designed with four supporting points, allowing four stable observation postures. Using the coordinates of the Niuheliang site, astronomical retro‑simulation shows that the posture angles of the artifact precisely match the operational parameters of the Big Dipper at dusk during the equinoxes and solstices between 3200 and 2900 BCE, with a combined deviation ≤ ±0.51°. XRF analysis confirms that the artifact is made of natural tremolite nephrite, and its elemental distribution is consistent with long‑term burial weathering, excluding the possibility of artificial aging. The results demonstrate that the artifact functioned both as a ritual symbol and a portable astronomical device, providing direct material evidence for prehistoric sky‑watching and time‑keeping practices.