Time Pieces at the National Planetarium

by Maganjeet Kaur

The simplest method to study the heavens is to stick a stick into the ground and observe its shadow at different times of day. This is the basis of sundials and the ‘stick’ is known as a gnomon. Apart from telling time of day, the resulting sun angles can also be used to tell the time of year.

Residing in a serene corner on the grounds of the National Planetarium are miniaturised replicas of three famous astronomical observatories from different parts of the world together with Malaysia’s own iconic timepiece. These are more sophisticated than the stick but they function essentially as gnomons. The four timepieces tell different stories, each compelling in its own way. The mysterious Stonehenge continues to hide its secrets, defying the hundreds of researchers bent on probing its depths. As you walk the grounds, gaze at the Guo Shou Jing Observatory and be amazed at the astronomer that conceived this marvel. Imagine the intellectual discourses that would have taken place at the Jai Singh Observatory, not only among local astronomers but also among those from afar as Bavaria, France, and Portugal. Recapture the excitement of Merdeka at the Merdeka Sun Clock.

Stonehenge

Stonehenge replica at the National Planetarium, Malaysia

Stonehenge, one of England’s most visited sites, was once sold at an auction for £6600! On 21 September 1915, Cecil Chubb, a barrister, was sent to an auction by his wife, Mary, to buy dining chairs; he returned home, instead, as the proud owner of a few acres of ruins, much to Mary’s chagrin. Fortunately, Chubb’s intentions were to protect the monument and, three years later, he donated Stonehenge to the nation, receiving a knighthood in exchange.

While the experts agree that Stonehenge was built in different phases by different groups of people, possibly for different functions, there is no common consensus on the constitution of the phases and the functions of the stones. The structure dates to around 3000 BCE, reaching its present shape around 1800-1500 BCE. The original structure was a henge, a circular flat area surrounded by a ditch, with the only difference from other henges being in its size – a whopping 100 metres across. Outer and inner banks surrounded the ditch and 56 circular cavities ran along the inner bank. Named Aubrey holes after the person who first noticed them, the cavities were believed to have initially contained bluestones but were used in a later period for cremation burials.

Stonehenge Phase 1 (around 3000 BCE). Image credit: http://arthistoryresources.net/stonehenge/stonehenge.html

The stones at the centre of the circle started being erected in different phases from around 2500 BCE, possibly beginning with the five trilithons. These were followed by the other stones including the bluestones, sarsen circle, heel stone, slaughter stone, and the four station stones. Attempts to link Stonehenge with observations of the heavenly bodies have mostly been refuted. It has been pointed out that it was not necessary to build a huge stone structure in order to make astronomical observations that could easily have be done using simpler tools. However, researchers acknowledge that Stonehenge is aligned on its northeast to southwest axis with the occurrences of solstices. There is also an interesting link between the heel stone and the midsummer solstice. There are a number of other connections with astronomy but a detailed discussion on the astronomical functions of the various stones, while fascinating, is outside the scope of this article.

The heel stone with Stonehenge in the background. This is a solitary piece of stone 4.7 metres tall with a tapered top. It sits outside the Stonehenge circle, at the start of an avenue that leads to Stonehenge. Image credit: Flicker (attribution: diamond geezer)

Guo Shou Jing Observatory

Replica of the Guo Shou Jing Observatory (Dengfeng Observatory) at the National Planetarium, Malaysia

This observatory was built in 1276 under orders by Kublai Khan, the founder of the Yuan dynasty in China. The observatory measures the sun’s shadow at noon and its variation throughout the year. It was named after the observatory’s creator, the renowned astronomer Guo Shoujing. The observatory lies near Gaocheng town, southeast of Dengfeng city in the Henan Province in China. Today, it is known as the Gaocheng Observatory or, more popularly, as the Dengfeng Observatory.

The observatory has two components: a platform formed by a truncated pyramid and a horizontal scale known as shigui.

The observatory at Gaocheng. Note the two components of the observatory: the large truncated platform and the horizontal scale in front of it. Image credit: Wikimedia Commons (attribution: Siyuwj, CC BY-SA 4.0)

The platform is 9.45 metres above ground level. Two staircases run up to the platform, on which has been built two rooms, joined by a single roof. The rooms raise the height of the structure to 12.62 metres. Each room has a window facing north and overlooking the horizontal scale below. The rooms also have a second window facing each other; a horizontal rod connects the two rooms through these windows. This rod acts as the gnomon. The height of the structure from the base to this horizontal rod is 9.75 metres, which is exactly 40 chi, a standard unit of measure in ancient China. A typical Chinese gnomon at the time was 8-chi tall (1.98 metres) – an example is the Tang period gnomon close to the vicinity of the Dengfeng Observatory. However, Guo Shoujing recognised a link between the height of the gnomon and the accuracy of the measurements; the resultant 40-chi gnomon at Gaocheng was thus innovative. It is said that Guo Shoujing’s move to a 40-chi gnomon was inspired by Middle Eastern astronomy, which had innovated large instruments, e.g. the Maragheh Observatory (1259 CE) in Iran.

The horizontal scale extended to the north of the large platform. The horizontal rod (gnomon) installed on the platform cast a shadow on the scale and this was the basis of the astronomical measurements. The horizontal scale, poetically known as the ‘sky-measuring ruler’, measures 31.19 metres in length or 128 chi. Two parallel troughs, linked at the ends, would have held water to check its level.

The two rooms above the platform. Their windows look out to the north. Image credit: Wikimedia Commons (attribution: Siyuwj, CC BY-SA 4.0)

The Dengfeng Observatory became the first of 27 observatories built by Guo Shoujing in various places in China. He used his observatories to develop a new Shoushi (season-granting) calendar. However, most of the information on the length of the sun’s shadow for this calendar came from another 40-chi gnomon he built in Dadu. The calendar, which started in 1281, would continue to be used for 364 years – until the end of the Ming dynasty.

Jai Singh Observatory

Replica of the Samrat Yantra (from the Jai Singh Observatory) at the National Planetarium, Malaysia

Pur means ‘city’ in Sanskrit and hence Jaipur, the breath-taking ‘pink city’, capital of Rajasthan, can be translated as the ‘City of Jai’. More specifically, it is the city of Maharaja Sawai Jai Singh II, who founded the city in 1726. Maharaja Jai Singh was an avid astronomer and he made a detailed study of Indian astronomical treatises. These go as far back as the Vedic texts (c. 1500-900 BCE), in which the study of stars and planets was known as Nakstravidya. He also studied Aryabhata’s famous treatise, Aryabhatiya (c. 476 CE), Varahmihira (c. 500 CE) and Brahmagupta (c. 598 CE). During the time that Jai Singh was carrying out his research, Middle Eastern and European knowledge of astronomy was very advanced and Jai Singh had their treatises translated into Sanskrit for his studies.

Sawar Jai Singh’s studies led him to recognise errors in the ephemerides, i.e. the trajectory of astronomical objects, used to calculate the imperial calendar and the astronomical tables. However, his existing brass instruments were not good enough for him to carry out the recalculations needed to correct the errors. Hence, he commissioned the construction of a jantar mantar (astronomical observatory) in Delhi. This would become the first of five observatories he would establish between circa 1721 and 1743. The others were at Jaipur, Ujjain, Varanasi, and Mathura. The observatory at Jaipur was the largest, in keeping with Jai Singh’s vision of his capital city having state-of-the-art architectural and astronomical edifices. With the exception of the observatory at Mathura, these observatories still exist and are heritage sites.

The information board at the planetarium specifies that the replica on its grounds is the Samrat Yantra (King of Instruments) from the Delhi Observatory. A Samrat Yantra is essentially a sundial usually with a triangular pyramid as its gnomon. It is flanked by two quadrants and the shadow of the gnomon on these quadrants measures the sun’s movement.

This drawing of the Delhi Samrat Yantra provides a good indication of its size. Illustrated by Thomas Daniell in 1815, currently in the collection of Wellcome Collection (Wikimedia Commons, CC BY 4.0)

The Samrat Yantra in Delhi has a colossal pyramid, measuring 21.3 metres in height. The hypotenuse of this right-angled triangular pyramid is parallel to the Earth’s rotation axis and the angle made by the hypotenuse and the horizontal is equal to the latitude of Delhi. The gnomon is flanked by two large quadrants, which lie on the plane of the equator. Their scales are graduated in a manner that allows the instrument to measure local time, right ascension, and declination. The Samrat Yantra allows measurements to a very high level of precision; both the Samrat Yantra at Delhi and Jaipur can measure time to an accuracy of two seconds.

Apart from the Samrat Yantra, the Observatory at Delhi has three other key instruments, each measuring different aspects of the movements of the heavenly bodies. These are: Misra Yantra, Jaya Prakasa Yantra and Rama Yantra. The Misra Yantra was built by Madho Singh, Jai Singh’s son. It is a compendium of five instruments including a Samrat Yantra.

Jantar Mantar at Delhi. Image credit: https://twitter.com/meissatech/status/481380967018287104 (modified to include labels)

Merdeka Sun Clock

Originally installed at Merdeka Park, the Merdeka Sun Clock was moved to the National Planetarium in 1997. The Merdeka Park, a public park opened on 20 April 1958, was located outside Merdeka Stadium, venue of the declaration of Independence on 21 August 1957.

The Sun Clock at its original location at Merdeka Park. Image credit: https://reclaimmerdekapark.wordpress.com/2013/09/18/memories-of-merdeka-park-part-2/

This sundial was the brainchild of Dato’ Stanley E. Jewkes, who had designed the Merdeka Stadium, Merdeka Park and, later, the National Stadium. His decision to include a sundial in the park was inspired by the solar clocks in India and by Stonehenge.

Malayan symbols have been weaved into both the gnomon and the bowl onto which the gnomon’s shadow is cast – the bowl is in the shape of a crescent and the pointer of the gnomon is an 11-pointed gold star representing the 11 states of Malaya (Sabah and Sarawak were not part of Malaya at that time). The clock measures time of year with zodiac signs used to represent months. Hour lines on a sundial are normally straight. However, the shape of the crescent bowl made this difficult and Jewkes compensated by building an equation of time into the lines. Two intersecting lines were drawn, differentiated by colour – one followed the sun as it moved north and the other as it moved south. An information board provides detailed instructions on measuring time using this solar clock.

Bibliography

Castleden, Rodney (2004) The Making of Stonehenge, Taylor & Francis e-Library.

Johnson-Roehr, Susan N. (2015) Observatories of Sawai Jai Singh II in C.L.N. Ruggles (ed.) Handbook of Archaeoastronomy and Ethnoastronomy, New York: Springer, pp. 2018-2028.

Lai Chee Kien and Ang Chee Cheong (2018) The Merdeka Interviews: Architects, Engineers and Artists of Malaysia’s Independence, Kuala Lumpur: Pertubuhan Akitek Malaysia.

Pearson, Mike Parker (2013) Stonehenge – A New Understanding: Solving the Mysteries of the Greatest Stone Age Monument, New York: The Experiment.

Powell, Jonathan (2019) From Cave Art to Hubble: A History of Astronomical Record Keeping, Springer ebook: https://doi.org/10.1007/978-3-030-31688-4

Pramod Kumar (1981) Sawai Jai Singh’s Observatories, Arts of Asia, Vol. 11 (5), pp. 127-134.

Xu Fengxian (2015) Dengfeng Large Gnomon in C.L.N. Ruggles (ed.) Handbook of Archaeoastronomy and Ethnoastronomy, New York: Springer, pp. 2111-2116.

Author: Museum Volunteers, JMM

Museum Volunteers, JMM Taking the Mystery out of History

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