Monthly Archives: March 2017

March Equinox 2017 – 5. March 20

In this last of the five spring equinox posts, we show you Sugisaka-san’s time-lapse photos on the day of spring equinox, March 20. We begin at 9:24 and show photos every 3 minutes, until time 9:48, while the last three photos were shot at 9:52, 9:54, and 9:57.

Following the sequence of twelve photos, we take a closer look at the oval spotlights at times 9:35 and 9:36. This is when the shape of the spotlight best matches the shape of the stone tool. And this conclusion matches with the photo at the bottom taken by Chika-san at 9:35:30.

Sugisaka March 20Ovals 320Chika 0320 93530




March Equinox 2017 – 4. March 19

On March 19, 2017, Kazuo Sugisaka took time-lapse photos of the Iwaya-Iwakage spotlight from high above looking down. We can watch the movement of the spotlight and how the shape changes. The first photo was taken at 09:21, the second at 09:23, and the subsequent photos at four-minute intervals. The last one was taken at 09:51.

Sugisaka 319


March Equinox 2017 – 3. March 20 Oval Spotlight

Spring equinox 2017 occurred on March 20 at around 7 pm in Japan. Chika-san has provided photos of the changing spotlight patterns on the floor of Iwaya-Iwakage. This time, she concentrated on the change in the shape of the spotko as it went from oval to triangular. It is fascinating that the same beam of sunlight can be so shaped by the megaliths!

We start with this photo taken at 9:21 on March 20 as the spotlight first appears as a partial oval on Stone a. Notice the right-angular carvings on the stone. They are meant as a kind of grid for tracking the movement of the spotlight during equinox time. See Guidebook, page 53.

The next three photos were taken at 9:25, 9:30:00 and 9:35:30 am on 20 March. They show the progression of the oval spotko on Stone a, toward our right which is east (as the morning sun moves westward). An oval stone measurement tool has been discovered inside Iwaya. We had suspected that its purpose is to serve as a template for the spotlight shape and size. So the oval stone was placed on Stone a at seemingly appropriate places. See pages 52 and 53 in the Guidebook.   

By time 9:43, the spotko has moved off Stone a and is starting to elongate. Time 10:23, the shape is now a triangle. An equilateral triangle at 12:02, a more acute triangle at 12:30. This is the triangular shape we saw in the previous post. And so, we have seen how the shape has changed from oval to obtuse to equilateral to acute triangle in the course of less than four hours.

In the next two posts, we show you time-lapse photos of the oval spotlight on March 19 and March 20.

We conclude that the oval stone was intended to serve as a template for the equinox observations on stone a. The construction of the megalith chamber and the associated markings and tools are an indication of the high sophistication of the ancient people who built this megalithic site in the mountains of Kanayama.

March Equinox 3 Photos only.pages


March Equinox 2017 – 2. Triangular Spotlight

Chika-san took photos in Iwaya-Iwakage on March 18, 2017, two days before the spring equinox. We showed you ten photos of the Iwaya opening, in Part 1. Here are ten spotko photos which correspond to those ten photos of the Iwaya opening. You can see the changes in the shape of the spotlight over the same 45-minute interval from 12:25 to 13:10. As more light is blocked by the middle megalith, the spotlight becomes narrower until it vanishes completely.

  Spotko 318



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


Hikari no Michi at Miyajidake Jinjya


There is a shrine in Fukutsu-shi, Fukuoka-ken with a shimenawa said to be, at 5 tons, the largest in Japan. Not only that, it is known for a spectacular sunset phenomenon. Set on the slope of Miyajidake, the Miyajidake Jinjya 宮地嶽神社 overlooking the city faces west toward the Japan Sea. A long flight of steps leads up to the main torii. From the shrine, the path seems to lead directly to the sea and Ai-no-shima island. This is the Hikari no Michi, the Path of Light.



Twice a year, the sun will set along a line connecting the shrine, the torii, the entrance path, the beach, and the island. The dates are around the 20th of October and February.  The Festival of the Setting Sun is held to commemorate the time when ancestors will come to sit between this world and the other world. At night the way is lit by 3,000 bamboo lamps on which prayers are written.

Chika-san visited the shrine on February 18, a few days early to avoid the expected large crowds. Her photos show the haiden with shimenawa and the view of the promenade from the torii to the sea. Finally, the sun sinks into the sea behind the Ai-no-shima, and night falls. The alignment will be straighter two or three days later as the sun moves further north.


The shrine has prepared a colorful brochure .

The reason for Chika-san’s and our interest in this solar event has to do with its closeness in time to the 10/23 and 2/19 astronomical cross-quarter observations at Kanayama Megaliths. These dates are around 60 days before and after the winter solstice. Observations made on cross-quarter dates assist in the determination of the winter solstice day. Further, careful data collection can also help determine a leap-year calendar. However, we have yet to find an astronomical purpose behind building the shrine to create the Hikari no Michi alignment. Yet, it does make for a splendid sight twice a year!