June 21 marks the Summer Solstice, and the rare celestial phenomenon known as the "upright pole with no shadow" returned to Taiji Cave in Zhaoqing's Xinghu National Wetland Park (肇庆星湖国家湿地公园太极洞), drawing astronomy enthusiasts, photographers, and visitors.
(Photo: Zhaoqing Fabu)
At midday, traditional Chinese folk music echoed through the cave as dancers performed beneath the natural skylight, adding a lively cultural touch to the scene. Visitors set up cameras early to capture the fleeting moment.
(Photo: Zhaoqing Fabu)
The phenomenon is a rare light-and-shadow effect that occurs near the Tropic of Cancer around the Summer Solstice. Located at 23°05′N, slightly south of the Tropic of Cancer (23°26′N), Taiji Cave features two natural skylights that allow sunlight to pour straight down to the cave floor, creating ideal conditions for the spectacle. Around 12:31 p.m., sunlight passed through the skylights and formed a vertical shaft of light on the cave floor. At that moment, neither a vertical pole nor a person standing inside the cave cast any shadow.
(Photo: Nanfang Plus)
The phenomenon follows a predictable pattern, occurring from June 19 to 23, with the moment appearing about 13 seconds later each day. This year, visitors were invited to witness the rare spectacle firsthand at Xinghu National Wetland Park.
Author | He Fengyu
