Category Archives: Seasonal observations

Summer Solstice 2018

June212018by KS

Kazuo Sugisaka made this report on this year’s summer solstice at Kanayama Megaliths. He arrived there a day early, June 20, and it was rainy all day. The next day, summer solstice day, it was cloudy during the morning and it seemed doubtful that the sun would come out. Fortunately, it turned sunny during the afternoon, and by sunset the sun could be seen sinking between two megaliths at Senkoku-ishi site. Summer solstice is a marker date on the Kanayama Solar Calendar. It marks the beginning of the 60-day late summer period.

Last year, we noticed a rather unusual flower blooming amongst the megaliths. This year, Sugisaka-san took this photo. It was identified as Cyrtosia septentrionalis, called tuchiakebi in Japanese. It is a member of the Orchidaceae family.

cyrtosia orchid by KS





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.




60 Days Before the Summer Solstice

From Friday, April 20th to Sunday 22nd, 2018
The above photo of the whole area, showing the Iwaya-Iwakage cluster on the left and the simulator building and the Senkoku-ishi grouping on the right, was taken from Highway 86 early in the morning of April 20.  Kanayama Megaliths blog has posted a new report dated April 26, 2018.   It is about the observation of 60 days before the summer solstice in the solar calendar of the Kanayama megaliths. It is the sunlight observation that tells the beginning of summer at the April 22 milestone date of the Kanayama Six-Season calendar.
At 6: 54 in the morning, light begins to stream from the top mountain. Summer observation is mainly at Senkoku-ishi. Looking at the position where the sun rises from the megalith, we see the sun just ascending from the mountain in the east at the Higashinoyama group. Now it’s past seven, and the light begins to reach Iwaya-Iwakage which is located somewhat higher than the Senkoku-ishi.
Then light begins to penetrate into the grotto of Senkoku-ishi. Around 7 a.m., sunight starts to shine on every single megalith. Although it starts out rather chilly, when the sun comes out, we feel the air of summer already.
Today Kobayashi-san is here, and there is a television interview going on. Kobayashi-san is standing in front of the shadow on Senkoku-ishi. this shadow is cast by the megalith in the lower right photo, below, on the morning of April 22.
As the sun rises higher, the grotto is illuminated, and the triangular face is very bright. On May 21, this face will be adorned with dashes of sunlight.

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.




Why are the Vedic and Jomon Calendars Identical?


The Hindu calendar which comes from the Vedas of 1200 BCE has six seasons called ritu.  The seasons and their dates are listed here.

Vasant     Spring         2/18 – 4/19

Grishma  Summer     4/19 – 6/21

Varsha     Monsoon     6/21 – 8/22

Sharad     Autumn       8/22 – 10/23

Hemant   Prewinter   10/23 – 12/21

Shishir     Winter        12/21 – 2/18

Six-season chartThe Jomon calendar of the Kanayama Megaliths has these six seasons.

Spring                           2/19 – 4/22

Early Summer            4/22 – 6/21

Late Summer              6/21 – 8/20

Autumn                        8/20 – 10/23

Early Winter               10/23 – 12/22

Late Winter                 12/22 – 2/19

The dates 2/19, 4/22, 8/20, and 10/23 are astronomical cross-quarter days. Compare the corresponding dates of the two calendars and we find that they differ only by 0, 1, 2, or 3 days. The summer solstice date is exactly right for India and for Japan. The winter solstice dates are 12/21 for India and 12/22 for Japan, so they do agree. The spring and autumn equinoxes are the middle date of both the Vedic and the Jomon calendars.

How the Jomon determined the seasonal dates.  You may be wondering what is the rule for the dates of 2/19, 4/22, 8/20, and 10/23 in the Jomon calendar. These are the dates when the sun’s altitude at noon is half-way between those of the winter solstice and the equinoxes for dates 10/23 and 2/19; half-way between those of the summer solstice and the equinoxes for dates 4/22 and 8/20. These dates are called yontobun in Japanese. It means dividing the zone of the sky between the highest and lowest altitudes into four parts.

How did the Vedic calendar determine the seasonal dates? Of the Hindu calendar it can be said:  Seasons follow the sun; months follow the moon; days follow both sun and moon. The seasonal dates of the Vedas roughly correspond to seasonal weather patterns, as can be seen from Monsoon as the late summer season. But why these exact dates? The calendar of the solar year is important for scheduling religious festivals. The ancient people of India were excellent astronomers who carefully studied the skies. They were familiar with the planets and the stars. So they must have had a good reason for selecting these particular dates. What was their reason?

Discussion.  From Internet articles about the Hindu religious calendar, we learned that government astronomers studied the position of the sun as it rose against the distant stars in order to determine the seasonal dates. This is not unlike the Jomon astronomers who used the position of the sun in the daytime sky to determine their seasonal dates. Once the Jomon people had set up the working megalithic observatory at Kanayama, they could simply watch the sunlight patterns to calibrate their calendar. They constantly monitored and updated their solar calendar so that it remained accurate to within one day.

While the dates of the six seasons of the Vedic and Jomon calendars agree closely, it is only a matter of time before the Vedic dates will drift slowly away, the effect of earth’s axial precession relative to the distant stars. The Jomon calendar may still be keeping good time, since it is watching the sun relative to Earth.






Himukae Ceremony on Winter Solstice 2017 – Part 2

IMGP0691Winter solstice sunrise at Asadori Myoujin by Chika

Chika-san has provided additional photos from the Himukae ceremony on the morning of winter solstice. Above is the splendid view of the sunrise, looking from Asadori’s torii.

The head priest who conducted the ritual had a very old scroll in his hands, so old that it was quite in tatters. And yet, this ceremony to greet the sun has come down through the ages from prehistoric times. We are fortunate to be able to participate even today with a precious activity of the Jomon people of Hinomoto.