Earth symbol

A variety of symbols or iconographic conventions are used to represent Earth, whether in the sense of planet Earth, or the inhabited world, or as a classical element. A circle representing the round world, with the rivers of Garden of Eden separating the four corners of the world, or rotated 45° to suggest the four continents, remains a common pictographic convention to express the notion of "worldwide". The current astronomical symbols for the planet are a circle with an intersecting cross, file:Earth [symbol (fixed width).svg|20px|?|alt=An equilateral cross enclosed in a circle], and a globus cruciger, [file:Globus cruciger (fixed width).svg|20px|♁]. Although the International Astronomical Union now discourages the use of planetary symbols, this is an exception, being used in abbreviations such as M_? or M_♁ for Earth mass.

History

The earliest type of symbols are allegories, personifications or deifications, mostly in the form of an Earth goddess.
Before the recognition of the spherical shape of the Earth in the Hellenistic period, the main attribute of the Earth was its being flat. The Egyptian hieroglyph for "earth, land" depicts a stretch of flat alluvial land with grains of sand. The Sumerian cuneiform sign for "earth, place" KI originates as a picture of a "threshing floor", and the Chinese character originated as a lump of clay on a potting wheel.

In Chinese mysticism, the classical element "Earth" is represented by the trigram of three broken lines in the I Ching.
The Western alchemical symbol for earth is a downward-pointing triangle bisected by a horizontal line. Other symbols for the earth in alchemy or mysticism include the square and the serpent.

In the Roman period, the globe, a representation of the spherical Earth, became the main symbol representing the concept.
The globe depicted the "universe" as well as the Earth.
File:INC-1870-r Солид. Никифор I и его сын Ставракий. Ок. 803—811 гг..png|thumb|upright|Byzantine Solidus coin with a Byzantine Emperor holding a globus cruciger in his right hand.
The globus cruciger is the globe surmounted by a Christian cross, held by Byzantine Emperors on the one hand to represent the Christian ecumene, on the other hand the akakia represented the mortal nature of all men.
In the medieval period, the known world was also represented by the T-and-O figure, representing an extremely simplified world map of the three classical continents of the Old World, viz. Asia, Europe and Africa.
Unicode encodes four characters representing the globe in the Miscellaneous Symbols and Pictographs block: