Chapter 1
Astronomy in the Tokugawa Period,
1603–1868
Abstract In the Tokugawa period, Japan was governed by a feudal government run
by the Tokugawa family with some economic and cultural flourishing. The role of
astronomers was the making of the lunisolar calendar, which occurred four times. In
parallel, Western cosmology from Aristotle to Newton was introduced by civilians,
particularly Dutch interpreters, in Nagasaki. The Tokugawa period is an age of
prehistory of modern astronomy in Japan.
1.1 Tokugawa Period and Astronomy
In 1603, a new central government was established by the Tokugawa family in Edo
(江戸, now Tokyo), apart from the Imperial Court in Kyoto. The country was
divided into many domains of feudal clan and governed by respective clan lord.
The Tokugawa government’s stable reign lasted from 1603 to 1868 (Nakayama
1969; Gordon 2003).
Japan was geographically distant from Western countries, and the Tokugawa
government adopted a policy of isolation from other countries to protect itself from
the propagation of Christianity. The Netherlands was the only country permitted to
have commercial trade at Nagasaki. The aim of this policy was the preservation of
traditional Chinese and Japanese thought, as the principal philosophical background
of Japanese culture.
In the Tokugawa period, astronomy was essentially limited to calendar reforms in
collaboration with Japanese mathematicians. Since these calendars were of a lunisolar type, the addition of a leap month was required to reconcile the calendar with
the actual seasons. This required lengthy and laborious work involving numerical
calculations, and calendar reform was implemented four times in 250 years (Araki
1940; Uchida 1986).
During this period, the translation of Dutch books with their contemporary
concept of Western cosmologies from the Aristotelian to the Newtonian was introduced into Japan. In 1720 the eighth Shogun Tokugawa Yoshimune (徳川吉宗),
permitted the importation of Western technical literature into Japan, especially
© Springer Nature Switzerland AG 2021
T. Kogure, The History of Modern Astronomy in Japan, Historical & Cultural
Astronomy, https://doi.org/10.1007/978-3-030-57061-3_1
1
Astronomy in the Tokugawa Period,
1603–1868
Abstract In the Tokugawa period, Japan was governed by a feudal government run
by the Tokugawa family with some economic and cultural flourishing. The role of
astronomers was the making of the lunisolar calendar, which occurred four times. In
parallel, Western cosmology from Aristotle to Newton was introduced by civilians,
particularly Dutch interpreters, in Nagasaki. The Tokugawa period is an age of
prehistory of modern astronomy in Japan.
1.1 Tokugawa Period and Astronomy
In 1603, a new central government was established by the Tokugawa family in Edo
(江戸, now Tokyo), apart from the Imperial Court in Kyoto. The country was
divided into many domains of feudal clan and governed by respective clan lord.
The Tokugawa government’s stable reign lasted from 1603 to 1868 (Nakayama
1969; Gordon 2003).
Japan was geographically distant from Western countries, and the Tokugawa
government adopted a policy of isolation from other countries to protect itself from
the propagation of Christianity. The Netherlands was the only country permitted to
have commercial trade at Nagasaki. The aim of this policy was the preservation of
traditional Chinese and Japanese thought, as the principal philosophical background
of Japanese culture.
In the Tokugawa period, astronomy was essentially limited to calendar reforms in
collaboration with Japanese mathematicians. Since these calendars were of a lunisolar type, the addition of a leap month was required to reconcile the calendar with
the actual seasons. This required lengthy and laborious work involving numerical
calculations, and calendar reform was implemented four times in 250 years (Araki
1940; Uchida 1986).
During this period, the translation of Dutch books with their contemporary
concept of Western cosmologies from the Aristotelian to the Newtonian was introduced into Japan. In 1720 the eighth Shogun Tokugawa Yoshimune (徳川吉宗),
permitted the importation of Western technical literature into Japan, especially
© Springer Nature Switzerland AG 2021
T. Kogure, The History of Modern Astronomy in Japan, Historical & Cultural
Astronomy, https://doi.org/10.1007/978-3-030-57061-3_1
1