Monthly Archives: September 2016

Autumn Equinox 秋分 2016


Iwaya-Iwakage Megalith Group   岩屋岩蔭遺跡巨石群

Autumn Equinox Observations   秋分の観測会

The first three days of autumn this year were rainy, and we could not make any spotlight observations. Finally, it dawned sunny on the 25th of September. The three photos were taken at Iwaya-Iwakage on that day.

秋分の観測会22, 23, 24日は雨天のためスポット光を見ることはできませんでした。ようやく25日に晴れ、添付写真はそのときのものです。


Photo 20160925_01.  This photo was taken from the outside, at the top of stone G, looking into the chamber of Iwaya-Iwakage. See the triangle of light at the lower left corner of the photo.  It is the spotlight beautifully striking the flat plane of stone F at around 40 degrees.

Photo 20160925_01 は、G石の上から撮影。F石の約40度のフラットな平面が美しい。内部へ射し込む三角形のスポット光が左下に見えます。


Photo 20160925_02.  Iwaya-Iwakage is flooded with light as visitors look on. The photo was taken around 12:00 noon.

Photo 20160925_02 は、見学者が光を浴びているところ。正午12:00頃。


Photo 20160925_03. Just before the light vanishes. Note that, after 30 days, the triangular spotlight will take on the same shape as the Sekimen flat stone (which can be seen on the left of the spotlight) 60 days before the winter solstice. This may be hard to believe, but it is true, as we will be reporting next month. Isn’t it amazing?

Photo 20160925_03 は、まもなく光が消えるとき。注目すべき点は、あと30日経過すると、三角形のスポット光は左の石面(Sekimen)の形と一体になる(冬至60日前)。

Spotlights and calendar accuracy

The spotlight observations increase the accuracy of the Kanayama Megaliths calendar. During the 30-day period(23 Sep. –  23 Oct.)the observed light moves a large amount every day. It is the fastest-moving time of the year. That is to say, just about now is the most important observation season!

金山巨石群はスポット光観測によって、暦の精度を上げています。ちょうど秋分から30日間のスポット光観測(23 Sep.—23 Oct.)が、光が1日に移動する距離が大きいときだから。つまりまさに今が観測シーズンです。



The Changing Length of Earth’s Day


Have you ever wondered how long is an Earth day, and is it changing? Well, although the day length is nominally 24 hours, it is not exactly so. It can vary from day to day, as well as from year to year. The amount of change may seem miniscule, and yet it will affect us as early as New Year’s eve, 2016.

A Leap-second will be added on December 31, 2016

“The U.S. Naval Observatory announced on July 6, 2016 that a leap second will be added to official timekeeping on December 31, 2016. That means your day and year – and everyone’s day and year – will officially be one second longer.”

Earth’s day-length is variable

The U.S. Naval Observatory chart above and article describe the variable length of day,

“The length of the mean solar day has increased by roughly 2 milliseconds since it was exactly 86,400 seconds of atomic time about 1.88 centuries ago (i.e. the 188 year difference between 2008 and 1820).  That is, the length of the mean solar day is at present about 86,400.002 seconds instead of exactly 86,400 seconds.  Over the course of one year, the difference accumulates to almost one second, which is compensated by the insertion of a leap second into the scale of UTC with a current regularity of a little less than once per year.  Other factors also affect the Earth, some in unpredictable ways, so that it is necessary to monitor the Earth’s rotation continuously.”

Earth’s Day is Getting Longer

Did you know that Earth’s day is getting longer? A tiny bit each year, to be sure, but it’s definitely getting longer and longer for Earth to rotate 360 degrees on its axis.

The Scientific American Magizine has posted an article entitled, “Fact or Fiction: The Days (and Nights) Are Getting Longer” at In this excerpt, NASA explains why.

“ Almost imperceptibly, however, Earth’s day–night cycle—one rotation on its axis—is growing longer year by year, and has been for most of the planet’s history.
“Forces from afar conspire to put the brakes on our spinning world—ocean tides generated by both the moon and sun’s gravity add 1.7 milliseconds to the length of a day each century, although that figure changes on geologic timescales. The moon is slowly spiraling away from Earth as it drives day-stretching tides, a phenomenon recorded in rocks and fossils that provides clues to the satellite’s origin and ultimate fate.”

Although “global warming is expected to shorten the day by 0.12 millisecond over the next two centuries by heating the oceans and changing the distribution of its mass,” clearly the effect of lunar and solar tides is greater by an order of magnitude (at least ten times the effect of global warming).

Today’s daylength


we find that:

“Date: Friday, September 2, 2016
24 hours, 0 minutes, 0.0008836 seconds (0.8836 milliseconds)
This day will be 0.0008836 seconds longer than 24 hours. This is the time it takes Earth to rotate 41.10 cm (16.18 in), as measured at the equator.”

So, on this date the day will be about 0.9 milliseconds longer than 24 hours.

How about calendars?

What about our calendars? The Kanayama Megaliths Solar Calendar will not be affected at all. Why? Because it is an observational calendar. it will always reflect what the sun’s path tells us. Leap years will always be known through the leap-year observations in Iwaya-Iwakage. This is the beauty of the Kanayama Megaliths Solar Calendar. It is and will always be correct.