Iwaya-Iwakage Spotlight, April 2017

April 22 was a special date on the Kanayama Solar Calendar. It is one of the astronomical cross-quarters, a yontobun date, a half-angle date. On this day, the sun’s path is halfway from that of equinox to summer solstice, and the solstice is about 60 days away. The Kanayama calendar makes observations on the four yontobun dates. 

Last year, the spotlight on the floor of the cavern that appeared on 7/22 vanished after striking the Sekimen-ishi on 10/23 as the sun headed south for the winter. This was reported in a previous post. Now the days are getting longer since the sun is returning to the north. And the spotlight has returned!

The spotlight returned on 2/19, and its path on the floor of the Iwaya cavern has been daily moving from north to south as the sun’s path in the sky changes daily from south to north. The spotlight will soon disappear on 5/21, when the light show at Iwaya-Iwakage ends. On that date light returns to Senkoku-ishi down the hill from Iwaya. Then Senkoku-ishi carries on the job of observing the sun over the summer season.

On April 23, 2017, Chika-san visited Iwaya-Iwakage. She took many photos of the movement of the spotlight on the floor of the Iwaya, as it moved from left to right for the viewer, which is from west to east, as the sun traveled in the sky from east to west. She shows how it began as a speck, grew into an oval shape and then shrank toward the end when only a streak of light on the vertical rock pointed to where it was last seen.

Iwaya 0423 Synopsis PDFPlease refer to page 52 of the Kanayama Megaliths Guidebook. Note the red line labelled: 11:30  8/20  4/22  Track of the spotlight. That is the line she was tracking. We thank Chika-san for these photos which give us a visual summary of the start on the floor (marked with observation lines) until disappearance of the spotlight on the rock at the far right.

The 14 photos shown were taken at the following times, ten minutes apart in the middle, a minute or two apart at beginning and end:

11:34     11:35     11:36     11:38

11:40     11:50     12:00     12:09

12:21     12:30     12:41     12:50

12:52     12:53