学会誌 要約紹介　通巻5　2023年1巻1号

Results of verifying the hypothesis that astronomical observations were conducted using the rock remains at Kamitani- Tachinomiya Shrine in Kyotango City, suggest that the east wall faced the direction of the summer solstice sunrise, rising from the right shoulder of Mount Kabuto. These suggests that ancient people likely used this rock to determine the arrival of the summer solstice and, at the same time, engaged in remote worship of Hitokuiiwa.

When we look at the summer solstice sunrise from the center of the sarsen circle of Stonehenge, we see it in the direction of the Heel Stone. I used an astronomical simulation software called “StellaNavigator” to reproduce the results for each construction stage of Stonehenge, and found that the azimuth of the summer solstice sunrise had shifted by about 1.0 degree from 2500 BC to the present. Since the Heel Stone was placed with high precision, I thought that the builders also observed the winter solstice sunset, and I started to search for unknown observation points.

An exploratory study of the megalithic astronomical observatory at Shira-ishi-no-hana, Matsuyama-shi, shows that the site has a logical, mathematical layout and can be used for accurate observations of solar and lunar cycles, among others. Several characteristics of previously identified points of interest support an interpretation that these megalithic objects are not a natural phenomenon but human artifacts. The site may have been built during the Jomon period or at a time when the sea level was lower than it is today.

The Uehara ruins in Ohmachi City, Nagano Prefecture are ruins of a village in the middle of the early Jomon period (5,000 years ago). There are two stone circles, one large and one small, made up of stone pillars. It is said to be a ritual site and an astronomical observation facility, but it is not certain. In this paper, we will clarify whether these two stone circles are astronomical observation facilities, what stone pillar they play, and why there are two large and small stone circles.

It is not clear whether the Jomon people had knowledge of azimuth、 solstices and equinoxes or not. In this paper、 we focus on 103 ancient tombs at Yudeno site. If there was any intention in building these ancient tombs (for example、 the axis of the tomb is determined in accordance with the direction of sunrise or sunset on the date of death)、 it should be found that the axial angle of these tombs deviate from the uniform distribution. Using 92 tombs except for 11 circular-shape tombs whose axial angles could not be clearly determined、 the deviation of axial angles from the uniform distribution is examined using Rayleigh test which is a technique of the direction statistics. As the result、 it is not obtained the positive result that the tomb group deviated from the uniform distribution. We therefore conclude that the tomb group at the Yudeno site could not prove the recognition of Jomon people about the azimuth、 solstices and equinoxes.

It is said that during the Jomon period there was no technology for transporting and assembling huge rocks. This paper clarified what the specific technology is for assembling huge rocks, and considered whether this technology was so advanced that it could not have existed in the Jomon period. As a result, assembling huge rocks by hand is possible if you have leverage technology, sled technology, roller technology, sled road technology, lubricant technology, and slope way technology. These technologies are "devices" created from experience. There is no reason to suppose that these techniques did not exist during the Jomon period.

The hōkakukiku shishinkyo mirrors, unearthed from the Hirabaru ruins—an ancient site of the Ito state—are categorized into two types: Type A, with the 'Zi' (Rat) of the Chinese zodiac facing north, and Type B, where it faces west. While Type A serves as the general directional reference, the Ito state introduced its distinctive Type B, establishing the twelve zodiac directions of Ito. It is believed that Queen Himiko, who assumed the throne as the ruler of the Kingdom of Wa, also embraced the same twelve zodiac directions as those of the Ito state in Wa. Her reason for adoption was to institute an east-facing Zi-Wu Line, positioning 'Zi' at the rear and 'Wu' at the forefront. At the eastern end of this line (referred to as "Matai"), the Yin deity, represented by the trigram Li (☲), is enshrined, while at the western end, the Yang deity, represented by the trigram Kan (☵), is enshrined. This Zi-Wu Line was designed to be oriented 3 to 9 degrees north when the distant star of the 'Willow' constellation is visible in the true east. The Central Axes of the Makimuku Palace ruins discovered in Kinai Makimuku are based on the eastward Zi-Wu Lines adopted by Queen Himiko. It employs the Incorrect Genbu Line, deviating 6.10 degrees north from true east, as the first-phase Central Axis, and another Incorrect Genbu Line, deviating 4.17 degrees, as the second-phase Central Axis. The presence of Sasahata Shrine at the eastern end (Matai) of the second-phase Central Axis, along with the mention in the Emperor Suinin Chronicle of Princess Yamatohime-no-mikoto visiting Sasahata in Uda to offer prayers to the deity Amaterasu, suggests that the Makimuku Palace ruins are likely the Makimuku Tamaki Palace of Emperor Suinin. The Sangō Island in the precincts of Jinrakuji Temple is identified as the site where the deity Amaterasu was enshrined in the village of Kasanui, as recorded in the Sujinki.

I believe that the development of astronomical archeology will increasingly require methods to scientifically and objectively verify whether the megalithic remains in question had an ancient astronomical observation function. Currently, the astronomical simulation software that is widely used by members of the society and the patterning and modeling based on the classification of rock remains proposed by the members of the society are applied to the megalithic group of Shiroishi, which is the subject of my own research. We verified whether it is effective in objective verification. As a result of verification, its effectiveness was confirmed.

During the Jomon period, agriculture was introduced to Japan. In an agricultural society, it is essential to understand seasonal changes in order to grow crops. It is especially important to know the time of the winter solstice and summer solstice, the turning points of the seasons.

At that time, there were places of ritual (Iwakura) where gods descended throughout Japan. Later, not a few shrines were built near those Iwakura. In order to verify the relationship between the approach path to shrines and seasonal changes in solar movement, we attempted a preliminary map-based survey of the approach directions of shrines throughout Japan. As a result, we found that some shrines have approach paths laid out in the sunrise and sunset directions of the summer and winter solstices. This paper reports on the possibility that shrine approaches may have played a role in understanding the seasonal changes in solar movement.