Zenith Sun and the Dashed Spotlight

Our previous post shows the day of no-shadow when the sun over Honolulu on July 15, 2024 is directly overhead at the zenith (see photo on the left). There was a similar solar event on May 27, 2024.

Earlier, Iwakage reported on the dashed spotlight of May 21, 2024 at the Kanayama Megaliths (photo on the right). There is a corresponding observation of the dashed spotlight on July 21, 2024.

What do these two pairs of solar observations have to do with each other? Does this image from page 48 of the guidebook help?

Recall that the summer solstice occurs on the day when the earth’s obliquity (the tilt of earth’s axis of rotation) is most tilted toward the sun. The summer solstice is indicated in the circular calendar on 6/21. The dashed spotlight at Kanayama Megaliths first appears on 5/21 when the sun in the sky is at just the right angle that it shines on the bumpy surface of the triangular panel. Then the sun moves higher in the sky and does not produce a dashed spotlight. The dashed spotlight reappears on 7/15 and makes a last appearance on 7/22.

It is the same phenomenon as the zenith sun over Hawaii and other tropical locations. On May 27, the sun was at the zenith over Honolulu, on its way north (so to speak). After June 21, the sun “headed south” and passed over Honolulu on July 15.

In a manner similar to that used by the ancient astronomers of Kanayama Megaliths, the astronomers of Hawaii could also use the zenith sun observations for their calendar. By my personal experience in viewing both types of solar observations, I would say that the spotlight observation is the more accurate of the two. It is rather difficult to position a upright pole and then to note when there is no shadow. Besides, the dashed spotlight makes quite a show!

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When the Sun is over your head: kau ka lā i ka lolo

The sun casts no shadow when it is directly overhead. Photo: Bishop Museum.

Places in the tropical zones of the Earth, between latitudes 23.44 degrees North and 23.44 degrees South enjoy the phenomenon of no noontime shadow twice a year when the sun is at the zenith. This is called the zenith passage of the sun, and the dates depend on the latitude of the location.

Here are some dates/times for places in Hawaii.

21.30 N May 27, 12:28; July 15, 12L37 Honolulu

19.7 N May 18, 12:16; July 23, 12:26 Hilo

18.9 N May 11, 12:19; July 27, 12:29 South Point, Hawaii Island

The time of this event in Hawaii is popularly called “lāhainā noon,” where the word lāhainā means cruel sun, perhaps because it can be scorchingly hot.

The proper Hawaiian term is kau ka lā i ka lolo, when the sun (ka lā) rests upon the brain (ka lolo).

Right at the equator, the zenith passage coincides with the equinoxes. At Chichén Itzá, latitude 20.68 degrees North, the zenith passage is experienced on May 26 and July 20, give or take a day. These zenith events apparently played a key role in the development of the Mayan calendar.

“When the sun passes overhead, the shadows disappear and the days when this happens assume a sacred significance for the people that live and lived within the tropics. ” From “Archaeoastronomy – The Zenith Passage of the Sun,” by Amelia Carolina Sparavigna.

July 15, 2024 12:37pm Honolulu. Photo by Iwakage.

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Summer Solstice Spotlight of the Marked Stone

Photo taken on June 16, 2024 inside the chamber of the Senkoku-Ishi Marked Stone megaliths. All photos by Shiho Tokuda of Kanayama Megaliths Research Center.

Ms Tokuda writes: Today, I am sending you a photo of the rectangular-oval spotlight taken on June 16th (five days before the summer solstice).

We confirmed that the shape of the spotlight was almost identical to the mark carved into the stone.

This may have been how ancient people welcomed summer and raised a toast in celebration!

Summer solstice has come again this year!

Iwakage Editor’s Notes

The above photo was taken at time 11:37 am. Note the oval spotlight on the ground that looks similar to the shape on the marked stone outside.

The photo below it was taken a few minutes later at time 11:42 am. It shows the spotlight shining on a flat white surface. At that time, the solar altitude was +77.4°. In the very same photo we see a print of a photo (with the dark blue background) taken nineteen years ago on June 20, 2005 at 11:40 am. The solar altitude at the time was the same, +77.4°. The shapes are nearly identical, and closely match the ovals carved on the outside of the chamber.

Photo taken of the spotlight on the floor on June 16, 2024 at time 11:42 am.

For reference, we show page 35 of the Kanayama Megaliths Guidebook. There are three oval shapes carved on Stone A of the Senkoku-Ishi Marked Stone group. Note Spotlight number 3, the largest of the three shapes. At the bottom of this page/scan is the spotlight shape seen above on summer solstice day, June 21.

Two previous posts can be seen here: https://iwakage.wordpress.com/2020/06/22/2020-summer-solstice/

and https://iwakage.wordpress.com/2016/06/28/summer-solstice-2016/

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Observations of May 21, 2024: Thirty Days Before the Summer Solstice

Dashed spotlight taken by Narita-san on May 21, 2024 at 12:55 pm.

The dashed spotlight observations take place on or around May 21, thirty days before the summer solstice, in the chamber of the Senkoku-ishi. The photo below by Ms. Chika shows Mr. Kazuo Sugisaka pointing to a tiny spot of light, taken at 12:54pm. Compare with the top photo taken by Narita-san one minute later, when five dashes can clearly be seen.

Here is one more photo by Ms. Chika. She calls this the “fantastic sun” shining through the cloudy skies, seen right at the top of the B-stone which faces Senkoku-ishi.

Thank you, Ms. Chika and Narita-san, for sharing your photos with us. These observations mark the summer solstice day, thirty days later. They are a part of the highly advanced Kanayama solar calendar system.

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Early Summer Season of the Kanayama Solar Calendar began April 22, 2024

Rising sun casts a shadow at the entrance to the chamber under Stone A. Photo by Kazuo Sugisaka taken on 04/20/2024 at 7:44am.

According to the Kanayama Megaliths Solar Calendar, early summer begins sixty days before the summer solstice. That date is April 22.

The above photo was taken by Kazuo Sugisaka on April 20, 2024 as the sun rose, lighting up and casting a shadow on the Stone A megalith of the Senkoku-Ishi cluster.

Ms. Chika went to the megaliths the following two days, April 21 and 22. She was disappointed that the skies were overcast and she could not capture the sun-and-shadow display. Nevertheless, I show one of her lovely photos below, and we can see the green leaves of the surrounding forest.

Thank you, Chika-san and Sugisaka-san for sharing your photos with us.

Photo taken by Ms. Chika on 04/21/2024 at 7:15am.

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Spring Equinox 2024

Kanayama Megaliths on spring equinox, March 21, 2024 at 08:19am by Ms. Chika

The vernal equinox arrived at the Kanayama Megaliths, and so did a number of visitors in spite of the snowfall the night before. At 09:38, they were able to view the oval spotlight with the exact shape as the ancient template stone.

The spring equinox setting sun was captured by Kazuo Sugisaka on March 20, 2024 at 16:46.

We thank Ms Chika and Mr. Sugisaka for sharing their photos with us.

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End of Winter, February 2024

This ground plan of the chamber of the Iwaya-Iwakage group is from the Kanayama Megaliths Guidebook, page 52. The walk-in entrance to the chamber is in the south, and the north “wall” is megalith F stone. There is a single opening through which a sunbeam can enter only during certain periods of the year: from 2/19 through 5/21, and again from 7/22 through 10/23. These dates are approximate. 

The ground tracks of the sunbeam are the red lines, and the dates specify the periods of those tracks. Starting on 2/19, the sunbeam is able to enter the chamber and illuminates the slab at the northern “rear.” A track starts at the left (western) end of the red line and moves in the course of the day to the right (eastern) end. Notice the long track of the spring and fall equinoxes, starting at 9:30 am and ending at 1:00 pm. 

It is clear that the track at the rear of the chamber is due to the winter sun which is low in the sky. By 5/21, the sun is so high that the sunbeam only enters for an extremely short time. After the summer solstice when the sun starts to travel at lower declinations, on 7/22 the beam will be able to enter once again. 

The tracks move progressively toward the rear until 10/23, after which the sunbeam no longer enters the chamber.

The date 10/23 is 60 days before the winter solstice, and 10/23 marks the beginning of the early winter season on the Kanayama Megaliths solar calendar. When the sunbeam reappears on 2/19, it is the end of the late winter season of 60 days. The winter solstice date is determined by other observations. 

Notice that a sample spotlight is shown as a triangle in the middle of the “floor.” The shape of the spotlight changes gradually, and when it reaches the rectangular slab at the north limit it has attained a rectangular shape similar to that of the slab itself.

This February, Ms Chika visited Iwaya-Iwakage on days 2/16 and 2/17 and took these photos at approximately 1:30 pm. The slab will be more fully illuminated on 2/19.

This photo was taken on 2/16/24 at 1:33pm. Notice that the spotlight has barely had a chance to illuminate the slab after grazing the surface of the “wall” of the F stone.

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Happy New Year, 2024, from Kanayama Megaliths

January 2, 2024. Stones C (left) and A (right) as seen from the hill. Photos by Kazuo Sugisaka.

Greetings from the Kanayama Megaliths! January 2, 2024 was a lovely, sunny day. This unusual view of the two large stones near the road was shot by Kazuo Sugisaka from up above near Stone D. The path takes one to Iwaya-Iwakage further up the hill under a brilliant blue winter sky.

Iwaya-Iwakage in sun and shade on January 2, 2024.

Thanks to Sugisaka-san, we can enjoy these scenes from the Kanayama Megaliths. Happy New Year to all!

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Winter solstice at Iwaya-Iwakage

Shiho tokuda points to the light from the rising sun striking the G-stone in Iwaya-Iwakage of December 25, 2023 at 10:18am. All photos by Ms. Chika.

We have relayed Kazuo Sugisaka’s report on the Winter Solstice observation of December 2023. Many other winter observations are possible at Iwaya-Iwakage on the hill at the Kanayama Megaliths. See pp 42-43 in the Kanayama Megaliths Guidebook. We have not previously reported on this phenomenon where the light of the rising sun strikes the bottom of the G-stone.

The morning sun crests the ridge on the east, as seen from inside the Iwaya-Iwakage. The eave of the small Shinto shrine is seen in the lower right half of the photo taken at 10:21 am.

We are grateful to our friends who share their photos and experiences at the Kanayama Megaliths. Happy New Year 2024 to All!

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Winter solstice sun 2023

The photo was taken at 16:04 on December 24th at the B-stone.

Winter Solstice 2023

Winter solstice arrived on Friday, December 22, 2023 at 03:27 UTC.

We have a report from Kazuo Sugisaka in Kanayama who sent us the striking photo above:

“On the day of the winter solstice, it sometimes snowed, and although it was sunny the next day, I couldn’t get a good photo of it, which is why the photo was taken on the 24th.”

Winter solstice, pronounced tōji in Japanese and written as 冬至, is archaically read as fuyu-itaru which means the arrival of winter.

Okunomichi posted this explanation of the winter solstice of 2020:

HAPPY NEW YEAR! WINTER SOLSTICE 2020

Thank you, Kazuo Sugisaka, for sharing your photo and your experience with us.

Best wishes for the new year to everyone in the world. Let peace prevail on Earth!

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