March Equinox 2017 – 1. Spotlight Opening

Spring has arrived at the Kanayama Megaliths! Its official arrival date was March 20, 2017 at around 7 pm in Japan. There is an interesting light show in the chamber of Iwaya-Iwakage. We have a series of posts with photos contributed by Chika-san and Sugisaka-san, volunteer observers of the Megaliths.

We have been interested in the varying shapes of spotlights in the caverns at Senkoku-ishi and Iwaya-Iwakage. Nominally, the basic shapes at both sites is a triangle. However, as the sun moves across the sky, the spotlights change their shapes. The shape of a spotlight is due to the sunlight entering a chamber through the opening between megaliths. In other words, the arrangement and the shapes of the megaliths themselves, together with the location of the sun in the sky, determine the shape of a spotlight.

We have an opportunity to study the spotlight in the Iwaya-Iwakage cavern. Chika-san was there two days before the spring equinox of 2017, and then on the equinox day itself. We show you a series of photos that she took of the opening where the sunlight enters to create a spotlight on the Iwaya floor. Changes are subtle, yet significant. The photos were taken at intervals of five minutes, beginning at around 12:25 on March 18, 2017, and ending at 13:10. We will in the next post show you the spotlight patterns on the floor of Iwaya.

Spotlight opening 318 2017