There are thousands of stars visible in our night sky, even from the city. Ancient astronomers or stargazers devised a simple yet brilliant way to remember when and where to see each of these stars – drawing constellations! The ancient Greeks imagined 88 constellations in the night sky, while the ancient Chinese astronomers imagined more. But there’s a common trait in how these constellations were imagined. They were designed because of the link between what happened on Earth at the times when those stars rose in their night skies. While the Greeks and the Chinese used common stars to mark the arrival of the seasons, the time in which these stars were seen differed. This is mainly due to the hundreds of years’ difference between when myths and legends were first told in these 2 cultures.
In Chinese legends, the celestial sphere (an imaginary sphere of stars that surrounds Earth) is broken up into 5 parts called Palaces. There are Summer, Spring, Winter, Autumn and Central Palaces. The seasonal palaces contain asterisms (parts of constellations) that commemorate events that happened on Earth.
The arrival of summer in the modern era is marked by the Summer solstice around 21 – 23 June each year. In ancient times, the Greeks observed the great Summer Triangle and the Chinese used the Celestial Vessel to alert them of summer. The Celestial Vessel, in the common night sky that we are familiar with today, is part of the constellation Gemini.
Drought and rainy seasons were marked in both the ancient Greek and Chinese star charts. The constellation Aquarius was thought by the Greeks to be the god Ganymede pouring water down to fill our rivers, after he took pity on earthlings who were suffering from a long period of drought before the rising of his stars. For the Chinese, a period of drought was marked by the Great Fire that is represented by Antares today – the heart of Scorpius in Greek mythology.
Winter was marked by different stars in the two ancient cultures. The Chinese ushered in winter with the Emperor’s Black Banner rising with the Sun near to winter, reaching directly overhead on winter solstice. The Emperor’s Banner is made up of some stars from the constellation Sagittarius. The Greeks on the other hand marked arrival of winter with the Winter Triangle that is made up of stars Betelgeuse, Sirius and Procyon.
When winter was coming, Chinese women would start to weave clothes for their families. The most famous Weaver Fairy is represented by the brightest star of Lyra the Harp – Vega. But if you refer to the image above, Vega is one of the stars that make up the Greek’s Summer Triangle. This difference is due to the fact that the Chinese refer to the stars when they rise at sunrise, rather than after sunset.
Then comes our favourite season – Spring. Coincidentally, the farmers in both cultures rejoice upon the arrival of Spica. For the Chinese, this star is the smaller horn of Blue Dragon of the Spring Palace. The greater horn is represented by a brighter, white star – Arcturus. These 2 stars rise in the East at about the same time. While Spica is the crop held by the Greek goddess of Harvest Virgo, the Horn of the Blue dragon, for the Greeks, ploughs the field in the sky, which is also part of the constellation Virgo. But the difference in times when these folklores were told meant that the stars rose at different times in the same season. For the Greeks, Spica rose opposite sunset, whereas the Horn rose along with sunrise. Nonetheless, the Root of the Blue Dragon, also known as Libra, represented equal day and night, i.e. equinox.
The star asterisms mentioned above are visible with the naked eye and even in our city, Singapore. While most would think that Singapore is badly polluted with lights, our street lights are downward facing, which means that we have tried our best not to shine light upwards for the atmosphere to reflect. Thus, if you would like to see some stars and noticed that the skies are clear, try to find a dark spot in between lamp posts or in a park (safety first!) and look up around you.
If you would like a guide to show you how to start stargazing, follow us on www.facebook.com/SCObservatory where we bring you a different stargazing experience on alternate Fridays, 8pm to 10pm. Alternatively, when our Observatory is able to reopen, you may visit Science Centre Singapore’s Observatory, open on every Friday 7.45pm to 10pm (except public holidays). Our Science Educators and volunteers would be more than happy to show you the beauty of our star-filled sky.
Like to know more comparisons between asterisms in different cultures? Leave a comment below!
Written by Mok Li Hui
Illustrated by Lee Ai Cing