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| title | chunk | source | category | tags | date_saved | instance |
|---|---|---|---|---|---|---|
| Astronomical symbols | 1/3 | https://en.wikipedia.org/wiki/Astronomical_symbols | reference | science, encyclopedia | 2026-05-05T08:26:55.281815+00:00 | kb-cron |
Astronomical symbols are abstract pictorial symbols used to represent astronomical objects, theoretical constructs and observational events in European astronomy. The earliest forms of these symbols appear in Greek papyrus texts of late antiquity. The Byzantine codices in which many Greek papyrus texts were preserved continued and extended the inventory of astronomical symbols. New symbols have been invented to represent many planets and minor planets discovered in the 18th to the 21st centuries. These symbols were once commonly used by professional astronomers, amateur astronomers, alchemists, and astrologers. While they are still commonly used in almanacs and astrological publications, their occurrence in published research and texts on astronomy is relatively infrequent, with some exceptions such as the Sun and Earth symbols appearing in astronomical constants, and certain zodiacal signs used to represent the solstices and equinoxes. Unicode has encoded many of these symbols, mainly in the Miscellaneous Symbols, Miscellaneous Symbols and Arrows, Miscellaneous Symbols and Pictographs, Alchemical Symbols, and Miscellaneous Symbols Supplement blocks.
== Sun and Moon == The use of astronomical symbols for the Sun and Moon dates to antiquity. The forms of the symbols that appear in the original papyrus texts of Greek horoscopes are a circle with one ray () for the Sun and a crescent for the Moon. The modern Sun symbol, a circle with a dot (☉), first appeared in Europe in the Renaissance.
In modern academic writing, the Sun symbol is used for astronomical constants relating to the Sun. Teff☉ represents the solar effective temperature, and the luminosity, mass, and radius of stars are often represented using the corresponding solar constants (L☉, M☉, and R☉, respectively) as units of measurement.
== Planets ==
Symbols for the classical planets appear in many medieval Byzantine codices in which many ancient horoscopes were preserved. The written symbols for Mercury, Venus, Jupiter, and Saturn have been traced to forms found in late Greek papyrus texts. The symbols for Jupiter and Saturn are identified as monograms of the corresponding Greek names, and the symbol for Mercury is a stylized caduceus. According to A.S.D. Maunder, antecedents of the planetary symbols were used in art to represent the gods associated with the classical planets; Bianchini's planisphere, discovered by Francesco Bianchini in the 18th century, produced in the 2nd century, shows Greek personifications of planetary gods charged with early versions of the planetary symbols: Mercury has a caduceus; Venus has, attached to her necklace, a cord connected to another necklace; Mars, a spear; Jupiter, a staff; Saturn, a scythe; the Sun, a circlet with rays radiating from it; and the Moon, a headdress with a crescent attached. A diagram in Byzantine astronomer Johannes Kamateros's 12th century Compendium of Astrology shows the Sun represented by the circle with a ray, Jupiter by the letter Zeta (the initial of Zeus, Jupiter's counterpart in Greek mythology), Mars by a shield crossed by a spear, and the remaining classical planets by symbols resembling the modern ones, without the cross-mark at the bottom of the modern versions of the symbols for Mercury and Venus. These cross-marks first appear around the 16th century. According to Maunder, the addition of crosses appears to be "an attempt to give a savour of Christianity to the symbols of the old pagan gods."
The symbols for Uranus were created shortly after its discovery. One symbol, , invented by J. G. Köhler and refined by Bode, was intended to represent the newly discovered metal platinum; since platinum, commonly called white gold, was found by chemists mixed with iron, the symbol for platinum combines the alchemical symbols for the planetary elements iron, ♂, and gold, ☉. Another symbol, , was suggested by Joseph Jérôme Lefrançois de Lalande in 1784. In a letter to William Herschel, Lalande described it as "un globe surmonté par la première lettre de votre nom" ("a globe surmounted by the first letter of your name"). Today, Köhler's symbol is more common among astronomers, and Lalande's among astrologers, although it is not uncommon to see each symbol in the other context. Several symbols were proposed for Neptune to accompany the suggested names for the planet. Claiming the right to name his discovery, Urbain Le Verrier originally proposed the name Neptune and the symbol of a trident, while falsely stating that this had been officially approved by the French Bureau des Longitudes. In October, he sought to name the planet Leverrier, after himself, and he had loyal support in this from the observatory director, François Arago, who in turn proposed a new symbol for the planet (). However, this suggestion met with stiff resistance outside France. French almanacs quickly reintroduced the name Herschel for Uranus, after that planet's discoverer Sir William Herschel, and Leverrier for the new planet. Professor James Pillans of the University of Edinburgh defended the name Janus for the new planet, and proposed a key for its symbol. Meanwhile, German-Russian astronomer Friedrich Georg Wilhelm von Struve presented the name Neptune on December 29, 1846, to the Saint Petersburg Academy of Sciences. In August 1847, the Bureau des Longitudes announced its decision to follow prevailing astronomical practice and adopt the choice of Neptune, with Arago refraining from participating in this decision. The International Astronomical Union discourages the use of these symbols in journal articles, though they do occur. In certain cases where planetary symbols might be used, such as in the headings of tables, the IAU Style Manual permits certain one- and (to disambiguate Mercury and Mars) two-letter abbreviations for the names of the planets.
== Asteroids ==