Stonehenge, the British megalithic site, allows you to observe the sunrise on the summer solstice from the center of the ring of megaliths.This paper is an attempt to simulate the sunrise of the summer solstice in 2600 BC, when the megalithic circle was built, incorporating Google Earth images into the stellar navigator of the astronomical simulation software.Furthermore, from the center of the circle, it is assumed that there was a common view of the universe as in the Jomon period in Japan due to the arrangement of megaliths that serve as an indicator for Arctic star observation and the Milky Way observation.

Abstract: In Yamazoe village in Nara Prefecture where people have lived since the early days of the Jomon period , there is a beautiful mountain called "Kounoyama ". In the mountain are the rock group like a river and the megalith.It discovered that these were reflecting the Milky Way and the Summer Triangle and also reflecting the North Pole Star and the Winter Triangle. The arrangement of these rocks is assuming that Kounoyama is celestial sphere.Also, it thought that would reflected the starry sky of the Jomon period. Therefore, by using the astronomical simulation software, we tried to estimate the age of the ancient ruins that reflected the stars by comparing the positions and shapes of the stars in the Jomon period.

The Kanayama Megaliths Research Center has been investigating two megalith locations in Gifu Prefecture since 1997. From the Jōmon period, both sites have been making observations of the rising sun, continuing an ancient calendar. The first is the Kanayama Megaliths situated in a mountainous region of Gero City. Here there are megalith constructions that, through solar observations, divide into four zones the sun's span in the sky (the span traversed by the sun during the year between the summer and winter turning points). The days of these turning points were also noticed in ancient Egyptian monuments. While it would seem that a mountainous region is an unsuitable environment for making solar observations, spotlights entering the megalith grouping enables the determination of the count of days in a year as well as the four-year leap-year cycle. Furthermore, in the flat region of Nakatsugawa City stands Maruyama Jinja's Funa-iwa boulder, a large fish-shaped monument at the foot of a small mountain. On the mountain are a number of megaliths for making solar observations all four seasons of the year. This area has a lot of Jōmon settlements. The lifestyle of the Jōmon period was centered around the solar cycle. The ancient people who received the blessings of the natural world well knew the solar cycle. We are wondering where on this earth might there be other hidden megaliths constructed for the solar calendar.

Up to now, the three round instruments < Rikujin form disk(六壬式盤), Taiitsu nine palaces disk(太乙九宮占盤), the twenty-eight lunar mansions disk(二十八宿円盤)> from the tomb of the Marquis of Ruyin have been studied individually on the history of Chinese astronomy.This paper simulated the twenty-eight lunar mansions using astronomy software under an assumption that the three round instruments discovered from the same tomb have close astronomical relations.

As a result, the calendar of Rikujin form disk followed the equal dividing method on the twenty four seasonal datum points indicated by Taiitsu nine palaces disk. Rikujin form disk displayed the twenty-eight lunar mansions at the midnight (0:00am) which is the first time on a day in ancient China.And the twenty-eight lunar mansions disk made it clear to possess the function of the present star chart disk which makes the South Pole in heaven the revolving center.