How China changed astronomy
Jamie Carter reveals how China’s thirst for space knowledge traces back to ancient sky-lore
Our constellations come from ancient Greek and Roman mythology. Many of the brightest stars we see – such as Betelgeuse (Alpha (a) Orionis), Deneb (Alpha (a) Cygni) and Algol (Beta (b) Persei) – were named in Arabic by Islamic astronomers. What we overlook when we gaze at the night sky is the incredible influence of Chinese astronomers.
Everyone knows about the Chinese or Lunar New Year, which starts on the day after the first new Moon that falls between 21 January and 20 February (in the Gregorian calendar) and ends with the next full Moon. You may also know about the Chinese belief that solar eclipses occur when a dragon eats the Sun. What you may not know is that Chinese astronomers were the first to make a reliable recording of a total solar eclipse (780 BC) and the passing of Halley’s Comet (239 BC).
Chinese astronomers have been studying the night sky for longer than any other culture. The oldest star maps and the earliest records of sunspots have been unearthed by archaeologists in China, where a unique way of looking at the night sky developed about 1200 BC. Astronomers Gan De and Shi Shen are credited as the first to create star catalogues in the 4th century BC, and the Buddhist monk Yi Xing (below) conducted an astronomical survey in the 8th century AD to help with the prediction of solar eclipses.
China’s star lore divides the sky into four groups of 283 asterisms (‘xing guan’). Three of the groups are ‘enclosures’ of stars close to Polaris (Alpha (a) Ursae Minoris). Surrounding Polaris are the ‘Purple Forbidden enclosure’ (which includes Ursa Minor), the ‘Supreme Palace enclosure’ (including Virgo, Coma Berenices and Leo) and the ‘Heavenly Market enclosure’ (with Serpens, Ophiuchus, Aquila and Corona Borealis).
The fourth group comprises the ‘Twenty-Eight Mansions’ (groups of stars) that are themselves divided into four groups of seven symbols. Within these
symbols are many easily identifiable asterisms and star clusters. For example, within the ‘White Tiger of the West’ symbol (which is equivalent to Taurus, the Bull) are the ‘Shen’ (‘Three Stars’) and the ‘Mao’ (‘Hairy Head’) mansions – known in the west as Orion’s Belt and the Pleiades open cluster, respectively. It was in this ‘White Tiger of the West’ region of the night sky that, in AD 1054, Chinese astronomers saw a new and very bright star. It was a supernova, also noted by Japanese, Korean and Arab astronomers, which today we know as its remnant – the Crab Nebula, M1.
Grand future plans
With a pivotal place in astronomy’s past, China is also poised to influence its future. Recent years have seen a growth in astronomical and astrophysical science in China. It’s now the world’s second most prolific nation in astronomy and space research, after the US.
That thirst for astronomical knowledge is backedup by hardware and space missions. In 2016 the £127 million Five-hundred-meter Aperture Spherical radio Telescope (FAST) in Guizhou, southwest China, also nicknamed ‘Tianyan’ (‘Heaven’s Eye’), was opened to detect Fast Radio Bursts (FRBs) and pulsars (neutron stars formed in a supernova explosion with powerful magnetic fields). The world’s largest single-dish radio observatory, FAST’s importance has been accentuated by the demise of the Arecibo telescope. It looks set to become a world-class facility; astronomers using FAST have newly identified around 300 pulsars so far and want to use it to find the first pulsar outside the Milky Way. FAST will also be used for sky surveys, to search for exoplanets with magnetic fields, and to map gas clouds between stars. It will also listen for signals from any alien civilizations out there.
Even in just the last few months China’s reputation among the scientific community has sky-rocketed. The China National Space Administration’s Chang’e 5 mission – named after the Chinese goddess of the Moon – returned 1.7kg of samples from the Moon last December. The following month, China gave FAST an ‘open sky’ policy, offering up the dish to observations by astronomers worldwide. Then in February the CNSA’s Tianwen-1 spacecraft arrived at Mars.
As it prepares to make China only the second country to deploy a rover on the Red Planet, the CNSA is also on the cusp of launching a modular crewed space station, the ‘Tiangong’ (‘Heaven’s Palace’). Proof, if more were needed, that China continues to have its gaze fixed firmly on the stars.