The Japanese star globe and historical astronomy

Stars have been drawn onto the surface of this Japanese astronomical globe using different coloured inks. These colours represent the jia (houses) of traditional Chinese astronomy and indicate the makers interest in historical aspects of the subject.

A practical instrument

Manuscript inscription on the Japanese globe
Image 1 Manuscript inscription on the globe recording the date of manufacture. It also describes the historical sources for the stars shown, and informs the user that celestial bodies no longer visible are represented by open circles. Image © the Whipple Museum (Wh.5617).

We do not know who made this globe, but a Chinese inscription on the sphere tells us that the object was crafted in Tenmei yonen saiji kinoetatsu gogatsu, that is, "the fifth month of the forth year of Tenmei" (Image 1). Tenmai is the name of an era in Japan spanning the period 1781-1789, so the sphere can be identified as Japanese and dated to 1784.

The globe is less ornamental than the majority of Asian astronomical instruments that survive from the Edo period (1603-1868), such as the Japanese sundial pictured in Image 2. Stars are inked onto the paper surface, rather than being engraved on a costly metal sphere, as they would have been on courtly globes. The small size, low weight, and clarity of the characters suggest that the globe might have been used in teaching - the item could be readily carried around and the characters are easy to read. Alternatively, the globe might have been a prototype for a more luxurious instrument.

Chinese influence

Brass compass and scaphe dial
Image 2 19th-century Japanese brass hinged case holding compass and scaphe dial. Like the Japanese globe, this dial shows strong Chinese influence - the hour characters around the edge of the dial are Chinese, while the Japanese characters are shown in the bowl of the dial. Image © the Whipple Museum (Wh.0856).

The design of this globe demonstrates extensive Chinese influence. The horizon ring G  of the globe is marked with characters representing the twelve Chinese 'double-hours of day and night'. Chinese constellations such as the 'imperial concubine' and 'celestial emperor' were used, and represented with ball-and-stick diagrams, rather than the pictorial characters familiar from western astronomy.

History in astronomy

Image 3 Part of the globe featuring stars from the three jia (houses) of traditional Chinese astronomy in red, yellow and black ink. Image © the Whipple Museum (Wh.5617). View large image.

While we tend to see astronomy as an observational science, astronomers in the Chinese tradition took a great interest in historical aspects of their subject. On the Japanese globe here, stars are inked in different colours (Image 3) to indicate in which of the three traditional Chinese jia, or "houses", of astronomy they were first recorded. Stars that can no longer be seen are also nevertheless recorded. The way that the stars are mapped on this globe suggests that the maker was interested in historically focused Chinese astronomy.

This article is based on the work of Hilary Smith, 'An Eighteenth Century Japanese Celestial Globe', submitted for the MPhil degree, 2000.

Katie Taylor

Katie Taylor, 'The Japanese star globe and historical astronomy', Explore Whipple Collections, Whipple Museum of the History of Science, University of Cambridge, 2009 [http://www.hps.cam.ac.uk/whipple/explore/globes/japanesestarglobe/, accessed 25 November 2017]

 
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