During the summer observational season, the sun clears the top of Stone C, as seen from Stone A, near the middle. As page 31 of the Guidebook shows, the sun is at the exact center on summer solstice day, 6/21. That is as far north, i.e., to the left, as it can go.
The three photos above were taken by Chika-san on May 23 from 8:25 to 8:26 am. The sun on that day appeared slightly to the right of center because there are still around 29 days to go before summer solstice.
These photos were taken by Chika-san at sunrise on May 23, 2017 at Senkoku-ishi. We are looking at Stone A, standing near Stone C with our back to the rising sun. The first two photos were taken at 6:22 and at 6:28 am. Notice that the sun has risen and shines on the upper right part of Stone A, but the grottos are not yet illuminated. The third and fourth photos were taken at 6:36 and at 6:42 am. The shadow of Stone C on A is now clearly seen, and the lower grotto is still in shade at 6:36 but it is lit at 6:42am. The final photo is a close-up of the opening of the lower grotto at 6:42.
Please refer to page 30 in the Guidebook. The three photos shown on that page are dated 4/22, 6/21, and 8/20. The date of 4/22 is about 60 days before the summer solstice. The lower grotto is in deep shadow. The date of 6/21 is the summer solstice when the grotto is fully illuminated.
The photos we show above were taken around thirty days before the summer solstice. They show us how the lower grotto is gradually illuminated, minute by minute.
Ed. Note: This is the concluding section of our three-part report on winter solstice observations, 2016.
Winter Solstice 2016.12.21
Iwaya-Iwakage. 10:25 am. We have just returned from the climb up Higashinoyama. The light of the sun rising from the mountain is beginning to strike the Iwaya-Iwakage megaliths while the lower foreground is still in deep shadow. The sun rises from the mountain at 10:15, and it was ten minutes later. This spectacle is superbly calculated. The location is well-suited for receiving the light of winter. Shapes that illuminate the megalithic group are made from the time the sun rises from the mountain until it sinks. It’s hard to believe, but it is happening here.
Inside Iwaya-Iwakage, light is entering into the chamber. From inside at the back of the inclined surface, looking at the sky in the south, you can see that the sun is entering below this inclined surface. This tilt is set in accordance with the sun’s position 60 days before the winter solstice, so that it is very bright inside.
Senkoku-ishi Evening, around 4 o’clock at Senkoku-ishi. Sunset light has hit the B and B’ boulders. Originally the one stone was broken and is now sitting in two parts called B and B’. The part of the V where the light hits may mean that the original stone was placed there to capture light of the sun at the time of winter solstice.
Approximately 4:10 pm. The sun will soon hide in the mountains. It is possible to watch it from the mountain, up to near the time (4:30) when the sun sets to the horizon, because of the position of the megalith group in the mountain valley. This is also the place where, in the opposite direction, the summer solstice sun will rise. I think it can be said that the place has been carefully selected for the megalithic group!
Ed. Note: This ends our three-part report on Winter Solstice 2016. A new year begins. Happy New Year to all our readers!