300-year-old Lhasa observatory marks spring irrigation period with solar alignment.

Ancient Tibetan astronomy persists in Lhasa, with a 300-year-old observatory hosting a recent event. At 9:50 am, sunlight aligned with a stone marker, marking the start of the spring irrigation period for the region east of the Lhasa River. Astronomical observations continue to guide agricultural practices, according to the timing recorded in the 2024 Tibetan annual almanac.