Category Archives: Spotlights

Iwaya-Iwakage: Sixty Days Before Winter Solstice 2018

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Sunlight entering Iwaya-Iwakage on 2018.10.23 at 13:00


The sixty days before winter solstice, observed at Higashinoyama in early morning, was confirmed in Iwaya-Iwakage at around 1pm on October 23, 2018. There were clouds in the sky around that time, and cheers broke out whenever the spotlight on Sekimen-ishi stone appeared. Here are photos of the large spotlight at various times when it appeared (12:56, 13:05, and 13:09). Since we are facing north, to us the spotlight appears to move from west to east. The last photo shows the light has reached the right-hand edge of the Sekimen. Branches of trees have cast some shadows on the stone.

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Thirty Days After Summer Solstice


At Senkoku-ishi, the dashed spotlight tells us in a dramatic light-show when it is thirty days before and after the summer solstice. The Kanayama Megaliths Japanese blogsite has posted photos from this year’s July dashed spotlight observations. There were torrential rains in Western Japan in preceding days, followed by 39 C = 103 F high temperatures. Yet, many people came who had seen the NHK special on the Kanayama Megaliths just a couple of days prior.


The dashed spotlight could be seen for five days, growing stronger, then thinner. Even on the final day, we could see four dashes.


For other photos and the report in Japanese, please click on the above underlined link. As Shiho Tokuda reminds us in this translation from her blog:

“Because the year is not exactly 365 days, the appearance of light slightly changes even for observations on the same day every year. It is repeated approximately every four years. Although it is related to the leap year, it is difficult to determine a leap year by this observation because the movement of the sun every day as seen from the earth is small. ”

For a more accurate method for leap-year determination (in October 2019, for instance), the Kanayama Megaliths has the leap-year observation in Iwaya-Iwakage.



Order Kanayama Megaliths Guidebook Online

日本初!古代太陽暦の証を発見 金山巨石群「縄文」太陽観測ガイド

小林由来・徳田紫穂 〔著〕


The Guidebook of the Kanayama Megaliths was published by the Kanayama Megaliths Research Center. Copies can be ordered directly from the Research Center. The online shop can be linked here.  This linked page is in Japanese, and orders can only be shipped to addresses in Japan at this time. If you are an overseas customer and would like to inquire about placing a large order, you will find contact information at the bottom of the online shop page.




Leap-year Observation Spotlight of February 27 and 28

金山巨石群 閏年観測のスポット光

Kanayama Megaliths Leap-year Observation Spotlight of February 27 and 28

The topic of this post at the Kanayama blogsite is the leap-year observation at Stone b  in Iwaya-Iwakage. It takes place on 10/14 and 10/15 and is repeated on 2/27 and 2/28.   The photos for 2/27 and 2/28, when the light returns to the stone, are shown .




Of further interest is the ongoing study of the 128-year leap-year cycle. The  measurement of 6 cm was recorded. 

52 years have elapsed in the current 128-year cycle of the Kanayama Megaliths calendar. It will next be revised around the year 2094, 76 years from now. We consider the position of the light (in the photo) is as expected. This is in accordance with the theory described in the Guidebook, page 66, as shown at the top of this page.

The post’s concluding remarks were:

Although it is still cold this year, since the sun is steadily heading for spring, there is nothing to worry about. People in the Jomon period must have grasped the changing period of vegetation as well. Nevertheless, their power to build such a calendar building is great ….




February 19, 2018 Winter into Spring

金山巨石群 冬期120日間終了の光

Kanayama Megaliths 120 Days of Winter Ends 2018 21519

This is our excerpt from the blog posted by the Kanayama Megaliths Research Center at on 2018.02.22. 

The face of the Sekimen stone in Iwaya-Iwakage is lit by a spotlight for five days from February 15 to 19. February 19 marks the end of the 120-day winter season. (The exact number of days was 119.) The 120 days of winter can be divided into the 60 days of Early Winter ending on the Winter Solstice and the 60 days of Late Winter following the Solstice.


The Kanayama blogsite has posted two photos taken on 2018.02.19 at 13:23 and 13:33. Note how well the lower edge of the spotlight matches the edge of the Sekimen. Comparison of the two photos shows that the solar altitude has decreased during the ten minutes lapse, causing the spotlight to move higher “up” the stone face. The spotlight of 2/19 matches that of 10/23, because the sun’s altitude is the same on these two days.


Here is a view of the beam of light entering from the crevice above. Three megaliths form the crevice and shape the sunbeam in exactly the right way.




October 27, 2017 Sekimen-ishi Spotlight


October 27.  This is the last day of the year for viewing the spotlight on Sekimen-ishi. The light will return on February 15 of next year. Although Sekimen-ishi means Sekimen stone, it is not a stone separate from Stone F but rather a projection of the megalith itself. That makes it all the more amazing how well the spotlight matches the shape and size of Sekimen-ishi.


This special day, some of the regulars came and it was fun viewing the spotlight together. We had a splendid light show!


In the afternoon, six busloads of visitors came from a company in Osaka, three buses at a time. They were guided by Ms. Tokuda, Mr. Kobayashi, and Mr. Okudo. They also had the chance to walk the Kinkotsu-meguri through Old Town and have lunch at Hizan. Surely it was quite a memorable experience for the Osaka-ites.




October 23, 2017 After the Typhoon

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Typhoon 21 reached Kanayama the night of October 22. It had been cloudy all week and we were eager to view the spotlight on Sekimen-ishi in Iwaya-Iwakage.

DSC04710 side view of toriiOctober 23.  Monday morning dawned cloudy and rainy, and it seemed hopeless. But the sun appeared mid-morning and we dared to venture out to the megaliths at noon. The drive was fine, until — we got to the last bend in the road. There we were stopped by a roadblock. Due to fallen branches, we could not drive further.

We parked the car and hiked in. It wasn’t far to go. There were many sugi and hinoki branches on the road, but we could walk easily and avoid stepping into rivulets. The walk turned out to be refreshing. The stream that runs into the Mazegawa was full of water and rushing along. We crossed over the Myouken-hashi bridge.


DSC04703 Myouken-hashi sign

We were happy to arrive at the megalith grounds and all was well. The stream there was whiter than we’ve ever seen it.

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Megaliths are lovely after a rain. Their surfaces glisten in the sun. Leaves on plants and trees are a brilliant, glistening green. Flowers were blooming on the tea plants. Since tea is a camellia, the flowers of course resembled camellia flowers.

When we got to the entrance to the chamber of Iwaya-Iwakage, we could see the spotlight. Inside, the spotlight was already lighting up the Sekimen-ishi, skimming the face of Stone F, and some of it was spilling off the lower edge. The faithful team of sun and stone created a beautiful sight!