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November 15, 2019

October at the Kanayama Megaliths

by Harriet H. Natsuyama

Japan-Insights Expert Harriet H. Natsuyama ,  visiting Scholar at the Kanayama Research Center provided us with this report on her recent visit to the Kanayama Megaliths in Gifu Prefecture – a power spot of global significance she has introduced at Japan-Insights.jp in her eassay Jomon Astronomy , the Solar Calendar of the Kanayama Megaliths.

Harriet H. Natsuyama

October at the Kanayama Megaliths

There are some wonderful solar observation events that take place at the Kanayama Megaliths in October, as well as all through the year.
The three sites of megalithic constructions form a system for determining a high-accuracy solar calendar — complete with adjustments every four years and 128 years of the leap-year cycles. This calendar has been operating for 5,000 years or more.



Iwaya-Ikage, October 15, 09:30 ©Shiho Tokuda

Leap-year observation

One such determination of the leap year occurs every four years on October 15. This year 2019, is one of those four years. Naturally, I wanted to be there to see it.

I had booked my flight to Kansai Airport well in advance. Just before my departure, the news announced that super-typhoon Hagibis would make landfall on October 12, my planned arrival date. I delayed my trip and I missed the observation of October 15. I was deeply concerned that Kanayama would suffer flooding as it did last year.
After days of wind and rain, the sky over Iwaya Valley on October 15 cleared and a beautiful spotlight appeared in the chamber of Iwaya-Iwakage. Shiho Tokuda, researcher and official photographer, provided these photos.

The spotlight in Iwaya travels across the floor from west to east. At 09:30, the spotlight shone exactly on the tip of the triangular stone where Shiho Tokuda had placed the template stone – a stone shaped by the Jomon astronomers. This was the sign that a leap day would be inserted in the calendar after the second confirming observation of February 28. Therefore, in 2020, the Jomon solar calendar has a leap day, just as we do on our February 29.
What a coincidence of dates!


Iwaya-Ikage, October 15, 09:30 ©Shiho Tokuda

Iwaya-Iwakage (the cavern's megalith shade), sixty days before Winter Solstice

I arrived in Kanayama a few days later. Although the storm had passed, the days were cloudy and rainy. The next observation was to take place on October 23 to mark the coming of the winter solstice sixty days later. This date is one of the four dates of the year that divides the zone of the sun in the sky into four parts. The same observation would be repeated when the sun returned to the same spot in the sky 60 days after the winter solstice.

Visitors to Iwaya-Iwakage, guided by Shiho Tokuda, October 23 ©Harriet Natsuyama

Once more, nature smiled on us. My photos above show a sunny day with visitors to Iwaya-Iwakage, led by Shiho Tokuda. This would be the first autumn day that the same beam of light as the leap-year spotlight would shine on the flat part of the Sekimen-Ishi. This plane protrudes from the gigantic face of the megalith covering the Iwaya chamber, facing due south. The two photos below were taken around 12:44. They show (1) the spotlight on Sekimen-Ishi, and (2) the opening in Iwaya where the light comes in.

Spotlight on Sekimen-Ishi and the opening in Iwaya-Ikage where the sunlight shines in, October 23, 12:44 ©Harriet Natsuyama

Higashinoyama (Eastern Mountain), sixty days before Winter Solstice

This spot, too, has an observation event sixty days before and after the winter solstice. At 08:30 on October 23, a group of nine hikers assembled to climb this mountain, more than 1km eastwards of the Iwaya-Iwakage. They were led by Shiho Tokuda and Yoshiki Kobayashi, her fellow investigator of twenty years.

Sun rising in front of S-Stone, October 23, 09:34 ©Shiho Tokuda

On the winter solstice, observation will be made from the 9-meter long R-Stone as the sun rises over the mountain ridge. The observation of October 23, sixty days before the winter solstice, is made at the edge of the S-Stone. , also 9 meters long, sitting somewhat below the R-Stone at an upward angle of 35 degrees. The S-Stone does not observe the sunrise on winter solstice.
From below, next to the S-Stone, the sun cannot be directly observed during the 120 days of the winter season, when the sun’s solar altitude is less than 35 degrees.

The next time to observe the rising sun from S-Stone is around February 20, 2020.

Visit Harriet Natsuyama's blog here
Read her article on the Kanayama Megaliths at Japan-Insights.jp!

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