A newly discovered stone circle at the Isedotai site in northern Japan has been confirmed as a sophisticated Jomon-era astronomical sun-dial. The array of upright stones is perfectly aligned with the sunset on the Summer Solstice, providing the first physical evidence of the specific timing for communal sun-greeting festivals that took place over three millennia ago.
Archaeologists found layers of miniature clay figurines and ceremonial pottery shards buried at the foot of the central stone, suggesting that the solstice was celebrated with the offering of "spirit-dolls" to the sun deity. This find helps bridge the gap between prehistoric solar observations and the modern Matsuri traditions that continue to honor the changing seasons across Japan.