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☉ U+2609, ☉ SUN ← ☈ Miscellaneous Symbols ☊ →

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Wikipedia

The shield of the sun god Apollo, with a boss in the center. Medieval replacement of ⟨🜚⟩, the sun with a single ray, which in ancient times had replaced a sun orb surrounded by multiple rays.^[1]

Compare the Egyptian hieroglyph ⟨⟩ and the Chinese character ⟨⟩, both of which mean 'sun' and 'day'.

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1. (astronomy, astrology) Sol, the Sun.

   A subscript to variables in mathematical equations, such as π_☉ (solar parallax).

   • 1803, Robert Patterson, The Papers of Thomas Jefferson, volume 40 (in English), Princeton University Press, published 2013, page 71:

     Suppose the apparent angular distance of the sun & moon's nearest limbs [...] to be 110°.2′.30″ the app. alt of ☉'s lower limb measuring 20°.40′ and that of ☽'s lower limb 35°.24′

2. (astronomy) solar mass.

   Synonym: M_☉

   • 1939, Oppenheimer & Volkoff, “On Massive Neutron Cores”, in Physical Review, volume 55:

     For masses under ${\displaystyle \textstyle {\frac {1}{3}}}$☉ only one equilibrium solution exists

3. (botany) annual.^[2]
4. (alchemy) gold.
5. (rare) Sunday.

   Refers to the Latin phrase dies Solis, which literally means "Sun's day".

6. (philately) cancellation (with an ordinary post-office cancellation mark).
7. (chemistry, obsolete) hydrogen (Daltonian symbol).

   Technically, this should be red: ☉. May also be typeset ⊙.

• (sun, daytime): ☼
• (sun, gold): 🌞︎, 🜚 (obsolete)

• (astronomy): M_☉ – solar mass (as a unit of measurement for the masses of stars)

L_☉ – solar luminosity (as a unit of measurement).

R_☉ – solar radius (as a unit of measurement).

S_☉ – solar constant (as a unit of measurement).

• (alchemy): ☉⃞ (gold leaf, gold foil)

• (botany): ⚇ (biennial)
• (astrology): 🝵 (Solar eclipse)

• 
  An abstract variant
• 
  A decorative variant in the Netherlands
• 
  As a symbol for gold
• 
  Symbol on a gold background

• 𓇳 (hieroglyph for Sun)
• ⊙ (mathematics, computing)

Planetary symbols
· · · – · – · · · · · · · · · · – · · – · · · · · · · ·

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1. (Should we delete⁽⁺⁾ this redundant sense?) the sun
   • 1797, Sigismund Bacstrom, transl., Chemical Moon-Shine: Wherein is Demonstrated the True Subject of Philosophy, Where We are to Look for it, & How it is to be Prepared:

     The matter must be collected when the Ram is grasing. |: i.e. ☉ in ♈︎ :|

2. (Should we delete⁽⁺⁾ this redundant sense?) (alchemy) gold
   • 1650, Paracelsus, “Of the Nature of Things”, in John French, transl., A New Light of Alchymie, page 73:

     But that the five leſſer, and impurer Metalls, viz. ♀ ♃ ♄ ♂ and ☿ may be tranſmuted into the greater, pureſt, and moſt perfect Metalls, viz. into ☉ and ☾, it cannot be done without the Tincture, or Philoſophers ſtone.

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1. (cartography): city center

☉ m sg (genitive ☉lis); third declension

1. (alchemy) Abbreviation of sol (“sun”).
   • 1688, Caspar Cramer, Collegium chymicum, page 6:

     Sic ſunt homines, qui ad lumen candelæ non autem ☉lis cœcutiunt, morbus nyctalopia dicitur.

     Thus there are men who are blind to the light of a candle but not of the sun; the disease is called nyctalopia.

Third-declension noun, singular only.

Third-declension noun, singular only.

• ☉is

☉ n (genitive ☉rī); second declension

1. (alchemy) Abbreviation of aurum (“gold”).
   • 1701, Johann Christoph Sommerhoff, Lexicon pharmaceutico-chymicum latino-germanicum & germanico-latinum [Pharmaceutico-Chemical Lexicon, Latin-German and German-Latin], page 34:

     Aurum fulminans fit ex ☉ro in 🜆egis ſoluto

     Fulminating gold is made from gold dissolved in aqua regia

Second-declension noun (neuter).