Today, I write about “Astronomical observation.”
Astronomical observation was very important for ancient people.
About 1300 years ago, There are following documents.
“A.D. 682 , The thing similar to the flag of the color of fire appeared in the night sky , and moved north.”
This is considered to be aurora.
“A.D. 684 , The comet appeared in the northwestern night sky.”
This is considered to be Halley’s comet.
The ancient person considered signs of extraordinary astronomical events to be an omen of disaster.
Comet : The omen of flood damage
Aurora : The signs of war
Solar eclipse : The signs of decline of the country by misgovernment
They did not neglect astronomical observation.
The early 1600s, Japan was in trouble about a calendar.
Those days, the Chinese lunar calendar was used.
Since this calendar was used from 800 years ago, it was inaccurate by error.
Therefore, the calendar was different regionally.
For example, since the calendar of Kyoto and Edo (Tokyo) is different.
The talk between the Emperor and a general was planned.
The general was criticized behind time.
The shogunate needed the common exact calendar.
They requested it from Shibukawa Harumi.
Shibukawa Harumi is a famous astronomer in Edo.
He began to investigate the calendar.
He thought that the calendar made 400 years ago in China was the most exact.
He did prediction of a solar eclipse and a lunar eclipse, in order to verify the accuracy of a calendar.
His prediction came true mostly.
However, his prediction was wrong only once.
He thought and understood.
“The earth is round.”
He improved the calendar.
1683, He completed a calendar of Japanese origin and named his calendar the Yamatoreki.
Then, the calendar was used till 1872, being improved.
2012, a movie “Tenchimeisatu” that modeled him was released.
The end of the 19th century, it had already been explained that the earth’s axis is moving.
However, it has not been explained how does it move.
1900, International joint astronomical observation started.
The astronomer of each country observed the same star at the same latitude.
The observation place in Japan is Iwate.
That is a very cold area.
Kimura Hisashi observed carefully in the cold room.
He did not use heating in order to lessen the error of observation.
It was severe observation.
The observations of countries other than Japan had the same regularity.
It was said that observations of Japan cannot be trusted.
Kimura Hisashi observed again carefully.
His observations were completely the same.
He was sure that observations are right.
He did much calculation using the abacus.
And he derived the equation.
Δφ = X cos λ + Y sin λ + Z
After that, He won the Gold Medal of the Royal Astronomical Society in 1936.
1958, Jan Oort (The astronomer of the Netherlands) discovered supernova explosion in the Crab Nebula.
It was called great discovery.
He found old documents of Japan.
It was the document written by Fujiwarano Sadaie in 1054.
“Mid-April, near star of Tenkan ,The bright star appeared in east night sky.”
And he discovered supernova explosion.
Japanese ancient astronomer did good work.
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