The ancient Greeks knew this fact. How about the chinese? If not, when did they realize that the earth is a sphere? By themselves or from other people?
There appear to be conflicting accounts of when the Chinese came to view the earth as spherical. Chinese sources might suggest the 11th century, while western sources suggest the 17th century.
According to the sinologist Christopher Cullen, the Chinese believed the earth to be flat and square while the heavens were round until the introduction of European astronomy in the 17th century. Quoting Cullen's 1976 text "A Chinese Eratosthenes of the Flat Earth: A Study of a Fragment of Cosmology in Huai Nan tzu 淮 南 子" :
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 the egg was used by Chinese astronomers to describe the heavens :
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.
Further details are provided at wikipedia article on Flat Earth.
However, Joseph Needham, in his more recent 1993 text Chinese Cosmology reports that Shen Kuo (1031-1095) used models of lunar eclipse and solar eclipse to conclude that "celestial bodies" are round, not flat.
If they were like balls they would surely obstruct each other when they met. I replied that these celestial bodies were certainly like balls. How do we know this? By the waxing and waning of the moon. The moon itself gives forth no light, but is like a ball of silver; the light is the light of the sun (reflected). When the brightness is first seen, the sun (-light passes almost) alongside, so the side only is illuminated and looks like a crescent. When the sun gradually gets further away, the light shines slanting, and the moon is full, round like a bullet. If half of a sphere is covered with (white) powder and looked at from the side, the covered part will look like a crescent; if looked at from the front, it will appear round. Thus we know that the celestial bodies are spherical.
What is not clear here is whether or not Shen Kuo considered earth to be a "celestial body". If not, then perhaps Cullen's claim is the current view.