University of Hawaiʻi team discovers ancient Hawaiian calendar system at a Hawaiʻi Island heiau

New research has uncovered evidence that an ancient Hawaiian heiau (place of worship, shrine) served as a sophisticated seasonal calendar, demonstrating the advanced scientific knowledge of Native Hawaiian culture.

The research, published in Waka Kuaka, the journal of The Polynesian Society, examined the Hapaialiʻi heiau near Kahaluʻu Beach Park on Hawaiʻi Island.

The study was conducted by Professor Albert S. Kim from the University of Hawaiʻi at Mānoa’s Department of Environmental and Construction Engineering, and Brenton Sasaoka, a Native Hawaiian civil engineer who graduated from the combined bachelor’s and master’s program at Mānoa.

Supported by the National Science Foundation, their work represents one o the first scientific papers examining the scientific aspects of Native Hawaiian cultural structures.

Master engineers, astronomers

Using mathematical analysis and modern mapping technology, Kim and Sasaoka discovered that carefully positioned stones within the heiau aligned with sunset positions throughout the year, effectively creating a calendar system. The structure – dating back between 1411 and 1465 – helped ancient Hawaiians track seasonal changes crucial for agriculture and fishing—unexpectedly found for its desalination potential.

The research team found that the left-most pillar marked the winter solstice, associated with a season of precipitation and peace. In contrast, the right-most pillar indicated the summer solstice, traditionally linked to gathering and preparation for warfare. These astronomical alignments enabled Native Hawaiians to determine optimal times for various cultural practices and maintain sustainable resource management.

“This research shows how Hawaiʻi’s ancestors were master astronomers, Indigenous scientists and resource engineers who created precise architectural alignments to track seasonal changes, demonstrating the deep connection between Hawaiian cultural practices and basic scientific understanding of the mother nature,” Kim said. “By applying modern scientific methods to investigate and learn these sacred sites, we can better document and preserve the incredible technological achievements of Native Hawaiian civilization for future generations.”

Kim has focused his most recent work on increasing Native Hawaiian students’ participation in STEM education.

“Dr. Kim’s research is a perfect example of how we can employ Western science and engineering methodologies to understand and illustrate how our ancestors utilized science to do so many things,” said Melia Talagi, a Native Hawaiian assistant professor in civil engineering at the University of Hawaiʻi at Mānoa

The researchers emphasize that their work provides important insights into Indigenous science while acknowledging that further research is needed for a complete understanding of the heiau system.

“Professor Kim’s contributions are sorely needed, and more has to be performed to benefit the state of Hawaiʻi,” said Professor Phillip Ooi, the Department Chair for Environmental and Construction Engineering.

The heiau was reconstructed by Kamehameha Schools in 2007. The researchers deeply thank Māhealani Pai, cultural resource specialist at Kamehameha Schools, for sharing historical and cultural materials, and guidance on the construction, maintenance and treatment of heiau.