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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Flat Earth | 2/6 | https://en.wikipedia.org/wiki/Flat_Earth | reference | science, encyclopedia | 2026-05-05T09:19:56.188495+00:00 | kb-cron |
If you take a lighted candle and set it in a room, you may expect it to light up the entire interior, unless something should hinder, though the room be quite large. But if you take an apple and hang it close to the flame, so near that it is heated, the apple will darken nearly half the room or even more. However, if you hang the apple near the wall, it will not get hot; the candle will light up the whole house; and the shadow on the wall where the apple hangs will be scarcely half as large as the apple itself. From this you may infer that the Earth-circle is round like a ball and not equally near the sun at every point. But where the curved surface lies nearest the sun's path, there will the greatest heat be; and some of the lands that lie continuously under the unbroken rays cannot be inhabited.
==== East Asia ====
In ancient China, the prevailing belief was that the Earth was flat and square, while the heavens were round, an assumption virtually unquestioned until the introduction of European astronomy in the 17th century. The English sinologist Cullen emphasizes the point that there was no concept of a round Earth in ancient Chinese astronomy:
Chinese thought on the form of the Earth remained almost unchanged from early times until the first contacts with modern science through the medium of Jesuit missionaries in the seventeenth century. While the heavens were variously described as being like an umbrella covering the Earth (the Kai Tian theory), or like a sphere surrounding it (the Hun Tian theory), or as being without substance while the heavenly bodies float freely (the Hsüan yeh theory), the Earth was at all times flat, although perhaps bulging up slightly.
The model of an egg was often used by Chinese astronomers such as Zhang Heng (78–139 AD) to describe the heavens as spherical:
The heavens are like a hen's egg and as round as a crossbow bullet; the Earth is like the yolk of the egg, and lies in the centre. This analogy with a curved egg led some modern historians, notably Joseph Needham, to conjecture that Chinese astronomers were, after all, aware of the Earth's sphericity. The egg reference, however, was rather meant to clarify the relative position of the flat Earth to the heavens:
In a passage of Zhang Heng's cosmogony not translated by Needham, Zhang himself says: "Heaven takes its body from the Yang, so it is round and in motion. Earth takes its body from the Yin, so it is flat and quiescent". The point of the egg analogy is simply to stress that the Earth is completely enclosed by Heaven, rather than merely covered from above as the Kai Tian describes. Chinese astronomers, many of them brilliant men by any standards, continued to think in flat-Earth terms until the seventeenth century; this surprising fact might be the starting-point for a re-examination of the apparent facility with which the idea of a spherical Earth found acceptance in fifth-century BC Greece. Further examples cited by Needham supposed to demonstrate dissenting voices from the ancient Chinese consensus actually refer without exception to the Earth being square, not to it being flat. Accordingly, the 13th-century scholar Li Ye, who argued that the movements of the round heaven would be hindered by a square Earth, did not advocate a spherical Earth, but rather that its edge should be rounded off so as to be circular. However, Needham disagrees, affirming that Li Ye believed the Earth to be spherical, similar in shape to the heavens but much smaller. This was preconceived by the 4th-century scholar Yu Xi, who argued for the infinity of outer space surrounding the Earth and that the latter could be either square or round, in accordance to the shape of the heavens. When Chinese geographers of the 17th century, influenced by European cartography and astronomy, showed the Earth as a sphere that could be circumnavigated by sailing around the globe, they did so with formulaic terminology previously used by Zhang Heng to describe the spherical shape of the Sun and Moon (i.e. that they were as round as a crossbow bullet). As noted in the book Huainanzi, in the 2nd century BC, Chinese astronomers effectively inverted Eratosthenes' calculation of the curvature of the Earth to calculate the height of the Sun above the Earth. By assuming the Earth was flat, they arrived at a distance of 100000 li (approximately 200000 km). The Zhoubi Suanjing also discusses how to determine the distance of the Sun by measuring the length of noontime shadows at different latitudes, a method similar to Eratosthenes' measurement of the circumference of the Earth, but the Zhoubi Suanjing assumes that the Earth is flat.
=== Alternate or mixed theories ===
==== Mesopotamia ==== Although Mesopotamian cosmology is usually depicted as a flat disc of land floating in water, some texts describe a complex structure composed of vertical layers. For instance, KAR 307, a cuneiform text, depicts three layered earths. The "Upper Earth" is the land inhabited by mankind, the "Middle Earth" are subterranean Apsu waters ruled by Enki, and the "Lower Earth" is the underworld which has 600 Anunnaki. While none of the ancient Mesopotamian models were spherical, Professor Wayne Horowitz documents "significant variety" in different Mesopotamian cosmological texts, noting "disagreement between texts from different periods, of different genres, and even among texts from the same period and genre."
==== Greece: spherical Earth ====