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 (old sun symbol) 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 usage, the Sun symbol is used for astronomical constants relating to the Sun.[7] 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.[8][9][10][11]

Name Symbol Unicode
code point
Sun Sol
(dec 9737)
the Sun (the center of our planetary system)
(dec 128794)
🜚 the Sun with one ray
Sun with face
(dec 127774)
🌞︎ the face of the Sun or "Sun in splendor"
Name Symbol Unicode
code point
Moon, or first-quarter moon First quarter moon
(dec 9789)
☽︎ an increscent (waxing) moon
(as viewed from the northern hemisphere)
First quarter moon with face
(dec 127771)
full moon Full Moon
(dec 127765)
🌕︎ a white circle as it appears in the night sky
Full Moon with face
(dec 127773)
Moon, or last-quarter moon Last quarter Moon
(dec 9790)
a decrescent (waning) moon
(as viewed from the northern hemisphere)
Last quarter Moon with face
(dec 127772)
new moon New Moon
(dec 127761)
🌑︎ a new moon
New Moon with face
(dec 127770)

Symbols for the planets

Medieval depiction of the zodiac and the classical planets. The planets are represented by seven faces.

Symbols for the classical planets appear in many medieval Byzantine codices in which many ancient horoscopes were preserved.[2] The written symbols for Mercury, Venus, Jupiter, and Saturn have been traced to forms found in late Greek papyrus texts.[22] The symbols for Jupiter and Saturn are identified as monograms of the corresponding Greek names, and the symbol for Mercury is a stylized caduceus.[22] 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, produced in the 2nd century,[23] 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.[24]

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 seen in modern versions of the symbols. 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."[24]

The symbols for Uranus were created shortly after its discovery. One symbol, Uranus, 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 iron, ♂, and gold, ☉.[25][26] This symbol also combines the symbols of Mars (♂) and the Sun (☉) because in Greek mythology Uranus represented heaven, and represents the combined power of Mars's spear and the Sun.[27] Another symbol, Uranus, was suggested by Lalande in 1784. In a letter to 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").[28]

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[29] and the symbol of a trident,[30] while falsely stating that this had been officially approved by the French Bureau des Longitudes.[29] In October, he sought to name the planet Leverrier, after himself, and he had loyal support in this from the observatory director, François Arago,[31] who in turn proposed a new symbol for the planet (proposed symbol for planet Leverrier).[32] However, this suggestion met with stiff resistance outside France.[31] French almanacs quickly reintroduced the name Herschel for Uranus, after that planet's discoverer Sir William Herschel, and Leverrier for the new planet.[33] Professor James Pillans of the University of Edinburgh defended the name Janus for the new planet, and proposed a key for its symbol.[30] Meanwhile, German-Russian astronomer Friedrich Georg Wilhelm von Struve presented the name Neptune on December 29, 1846, to the Saint Petersburg Academy of Sciences.[34] 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.[35]

The International Astronomical Union discourages the use of these symbols in journal articles. 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.[36]

Name IAU
Symbol Unicode
code point
Mercury Me Mercury
(dec 9791)
Mercury's caduceus[17][37]
Venus V Venus
(dec 9792)
Venus's necklace (also interpreted as a "hand mirror"[17][37])
Earth E Earth
(dec 9793)
a globus cruciger[38]
(dec 128808)
🜨 globe with equator and a meridian[12][37]
(alternative characters with similar shape: U+2295 ⊕ CIRCLED PLUS; U+2A01 ⨁ N-ARY CIRCLED PLUS OPERATOR; U+1F310 🌐︎ GLOBE WITH MERIDIANS)
Mars Ma Mars
(dec 9794)
Mars's shield and spear[12][17][37]
Jupiter J Jupiter
(dec 9795)
the letter Zeta (for Zeus, the Greek equivalent to the Roman god Jupiter)[37]
Saturn S Saturn
(dec 9796)
Saturn's sickle or scythe[12][17][37]
Uranus U Uranus
(dec 9954)
the element platinum[25][26]
(dec 9797)
a globe surmounted by the letter H (for Herschel, who discovered Uranus)[28]
(more common in older or British literature)
Neptune N Neptune
(dec 9798)
Neptune's trident[12]
Neptune (alternate symbol)
(dec 11209)
a globe surmounted by the letters "L" and "V", (for Le Verrier, who discovered Neptune)[32][37]
(more common in older, especially French, literature)

Symbols for minor planets

Following the discovery of Ceres in 1801 by the astronomer and Catholic priest Giuseppe Piazzi, a group of astronomers ratified the name, which Piazzi had proposed. At that time, the sickle was chosen as a symbol of the planet.[39]

The symbol for 2 Pallas, the spear of Pallas Athena, was invented by Baron Franz Xaver von Zach, who organized a group of twenty-four astronomers to search for a planet between the orbits of Mars and Jupiter. The symbol was introduced by von Zach in his Monatliche correspondenz zur beförderung der erd- und himmels-kunde.[40] In a letter to von Zach, discoverer Heinrich Wilhelm Matthäus Olbers (who had named the newly discovered asteroid) expressed his approval of the proposed symbol, but wished that the handle of the sickle of Ceres had been adorned with a pommel instead of a crossbar, to better differentiate it from the sign of Venus.[40]

German astronomer Karl Ludwig Harding created the symbol for 3 Juno. Harding, who discovered this asteroid in 1804, proposed the name Juno and the use of a scepter topped with a star as its astronomical symbol.[41]

The symbol for 4 Vesta was invented by German mathematician Carl Friedrich Gauss. Dr. Olbers, having previously discovered and named 2 Pallas, gave Gauss the honor of naming his newest discovery. Gauss decided to name the new asteroid for the goddess Vesta, and also designed the symbol (Vesta): the altar of the goddess, with the sacred fire burning on it.[42][43][44] Other contemporaneous writers use a more elaborate symbol (Vesta) instead.[45][46]

Karl Ludwig Hencke, a German amateur astronomer, discovered the next two asteroids, 5 Astraea (in 1845) and 6 Hebe (in 1847). Hencke requested that the symbol for 5 Astraea be an upside-down anchor;[47] however, a pair of balances was sometimes used instead.[14][48] Gauss named 6 Hebe at Hencke's request, and chose a wineglass as the symbol.[49][50]

As more new asteroids were discovered, astronomers continued to assign symbols to them. Thus, 7 Iris had for its symbol a rainbow with a star;[51] 8 Flora, a flower;[51] 9 Metis, an eye with a star;[52] 10 Hygiea, an upright snake with a star on its head;[53] 11 Parthenope, a standing fish with a star;[53] 12 Victoria, a star topped with a branch of laurel;[54] 13 Egeria, a buckler;[55] 14 Irene, a dove carrying an olive branch with a star on its head;[56] 15 Eunomia, a heart topped with a star;[57] 16 Psyche, a butterfly wing with a star;[58] 17 Thetis, a dolphin with a star;[59] 18 Melpomene, a dagger over a star;[60] and 19 Fortuna, a star over Fortuna's wheel.[60]

Johann Franz Encke made a major change in the Berliner Astronomisches Jahrbuch (BAJ, Berlin Astronomical Yearbook) for the year 1854, published in 1851. He introduced encircled numbers instead of symbols, although his numbering began with Astraea, the first four asteroids continuing to be denoted by their traditional symbols. This symbolic innovation was adopted very quickly by the astronomical community. The following year (1852), Astraea's number was bumped up to 5, but Ceres through Vesta would be listed by their numbers only in the 1867 edition. The circle later became a pair of parentheses, and the parentheses were sometimes omitted altogether over the next few decades.[14]

A few asteroids were given symbols by their discoverers after the encircled-number notation became widespread. 26 Proserpina, 28 Bellona, 35 Leukothea, and 37 Fides, all discovered by German astronomer Robert Luther between 1853 and 1855, were assigned, respectively, a pomegranate with a star inside;[61] a whip and spear;[62] an antique lighthouse;[63] and a cross.[64] 29 Amphitrite was named and assigned a shell for its symbol by George Bishop, the owner of the observatory where astronomer Albert Marth discovered it in 1854.[65]

Pluto's name and symbol were announced by the discoverers on May 1, 1930.[66] The symbol, a monogram of the letters PL, could be interpreted to stand for Pluto or for Percival Lowell, the astronomer who initiated Lowell Observatory's search for a planet beyond the orbit of Neptune.[12][67]

Minor planets
Name Symbol Unicode
code point
1 Ceres 1 Ceres
(dec 9907)
a handle-down sickle;[37]
cf. the handle-up sickle symbol of Saturn
2 Pallas 2 Pallas
(dec 9908)
a spear[40][48]
3 Juno 3 Juno
(dec 9909)
a scepter topped with a star[41]
3 Juno
4 Vesta 4 Vesta
(dec 9910)
an altar with fire on it[42][44]
4 Vesta
5 Astraea 5 Astraea
an inverted anchor[47]
5 Astraea (alternate symbol)[70] U+2696
(dec 9878)
a pair of balances[37][48]
6 Hebe 6 Hebe
N/A N/A a wineglass[49]
6 Hebe
(dec 127863)
7 Iris 7 Iris
N/A N/A a rainbow with a star inside it[51]
7 Iris
8 Flora 8 Flora
(dec 9880)
a flower[51]
9 Metis 9 Metis
N/A N/A an eye with a star above it[52]
10 Hygiea 10 Hygiea
N/A N/A a serpent with a star[53]
10 Hygiea
(dec 9877)
a Rod of Asclepius
11 Parthenope 11 Parthenope
N/A N/A a fish with a star[53]
11 Parthenope
N/A N/A a harp[48]
12 Victoria 12 Victoria
N/A N/A a star with a branch of laurel[54]
13 Egeria 13 Egeria
N/A N/A a buckler[55]
14 Irene 14 Irene
N/A N/A a dove carrying an olive-branch in its mouth and a star on its head[56]
15 Eunomia 15 Eunomia
N/A N/A a heart with a star on top[57]
16 Psyche 16 Psyche
N/A N/A a butterfly's wing and a star[58]
17 Thetis 17 Thetis
N/A N/A a dolphin and a star[59]
18 Melpomene 18 Melpomene
N/A N/A a dagger over a star[60]
19 Fortuna 19 Fortuna
N/A N/A a star over a wheel[60]
26 Proserpina 26 Proserpina
N/A N/A a pomegranate with a star inside it[61]
28 Bellona 28 Bellona
N/A N/A Bellona's whip and spear[62]
29 Amphitrite 29 Amphitrite
N/A N/A a shell[65]
35 Leukothea 35 Leukothea
N/A N/A an ancient lighthouse[63]
37 Fides 37 Fides
N/A N/A a Latin cross, in fact showing broadened and rounded endings[64][73]
134340 Pluto Pluto
(dec 9799)
a PL

The zodiac symbols have several astronomical interpretations. Depending on context, a zodiac symbol may denote either a constellation, or a point or interval on the ecliptic plane.

Lists of astronomical phenomena published by almanacs sometimes included conjunctions of stars and planets or the Moon; rather than print the full name of the star, a Greek letter and the symbol for the constellation of the star was sometimes used instead.[74][75] The ecliptic was sometimes divided into 12 signs, each subdivided into 30 degrees,[76][77] and the sign component of ecliptic longitude was expressed either with a number from 0 to 11[78] or with the corresponding zodiac symbol.[77]

In modern academic usage, all the constellations, including the twelve of the zodiac, have dedicated three-letter abbreviations.[79] The zodiac symbols are also sometimes used to represent points on the ecliptic, particularly the solstices and equinoxes. Each symbol is taken to represent the "first point" of each sign.[80][81] Thus, ♈︎ the symbol for Aries, represents the March equinox; ♋︎, for Cancer, the June solstice; ♎︎, for Libra, the September equinox; and ♑︎, for Capricorn, the December solstice.

Name IAU
Signs Degrees Symbol Translation Unicode
code point
Aries Ari[36] 0 Aries
ram[82] U+2648
(dec 9800)
Taurus Tau[36] 1 30° Taurus
bull[82] U+2649
(dec 9801)
Gemini Gem[36] 2 60° Gemini
twins[82] U+264A
(dec 9802)
Cancer Cnc[36]
3 90° Cancer
crab[82] U+264B
(dec 9803)
Leo Leo[36] 4 120° Leo
lion[82] U+264C
(dec 9804)
Virgo Vir[36] 5 150° Virgo
virgin[82] U+264D
(dec 9805)
Libra Lib[36] 6 180° Libra
scales[82] U+264E
(dec 9806)
Scorpius Sco[36] 7 210° Scorpius
scorpion[82] U+264F
(dec 9807)
Sagittarius Sgr[36] 8 240° Sagittarius
archer[82] U+2650
(dec 9808)
Capricornus Cap[36] 9 270° Capricornus
goat[82] U+2651
(dec 9809)
Aquarius Aqr[36] 10 300° Aquarius
water bearer[82] U+2652
(dec 9810)
Pisces Psc[36] 11 330° Pisces
fish[82] U+2653
(dec 9811)

Other symbols

Symbols for aspects and nodes appear in medieval texts, although medieval and modern usage of the node symbols differ; the modern ascending node symbol (☊) formerly stood for the descending node, and the modern descending node symbol (☋) was used for the ascending node.[3] In describing the Keplerian elements of an orbit, ☊ is sometimes used to denote the ecliptic longitude of the ascending node, although it is more common to use Ω (capital omega), which was originally a typographical substitute for the astronomical symbol.[83]

The symbols for aspects first appear in Byzantine codices.[3] Of the symbols for the five Ptolemaic aspects, only the three displayed here—for conjunction, opposition, and quadrature—are used in astronomy.[84]

Symbols for a comet (☄) and a star (Astronomical symbol for star.svg) have been used in published astronomical observations of comets. In tables of these observations, ☄ stood for the comet being discussed and Astronomical symbol for star.svg for the star of comparison relative to which measurements of the comet's position were made.[85]

Other symbols
Name Symbol Unicode
code point
ascending node ascending node
(dec 9738)
descending node descending node
(dec 9739)
conjunction conjunction
(dec 9740)
opposition opposition
(dec 9741)
quadrature quadrature
(dec 9633)
comet comet
(dec 9732)
star star
(dec 9733)

See also

Original: Original: