Astronomical symbols

This article contains special characters. Without proper rendering support, you may see question marks, boxes, or other symbols.

This excerpt from the 1833 Nautical Almanac demonstrates the use of astronomical symbols, including symbols for the phases of the moon, the planets, and zodiacal constellations.

"Designation of celestial bodies" in a German almanac printed in 1850^[1]

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.^[2][3] New symbols were further invented to represent many newly discovered planets and minor planets discovered in the 18th to the 20th 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,^[4] 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 formally assigned code points to most symbols, mainly in the Miscellaneous Symbols Block^[5] and the Miscellaneous Symbols and Pictographs Block.^[6]

Symbols for the 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.^[3] The modern Sun symbol, a circle with a dot (☉), first appeared in Europe in the Renaissance.^[3]

In modern academic writing, the Sun symbol is used for astronomical constants relating to the Sun.^[7] T_eff☉ 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.^{[8][9][10][11]}

Sun

Name	Symbol	Unicode code point	Unicode display	Represents
Sun	[12][13][14]	U+2609 (dec 9737)	☉	the Sun (the center of our planetary system)
	[3]	U+1F71A (dec 128794)