Sun of May

The Sun of May (Spanish: Sol de Mayo) is one of the national symbols of the Río de la Plata countries of Argentina and Uruguay, featured in their respective flags and coats of arms. It is named after the May Revolution of 1810, the event that catalyzed the Independence process in the Viceroyalty of the Río de la Plata. It is also known as the Inca sun (Spanish: "sol incaico"), since the most widespread explanation of its meaning is that it represents Inti, the solar god of the Incas. However, no contemporary sources confirm an Inca origin for the symbol and this claim which emerged later with the development of Argentine historiography. The Sun of May design appears to be heir to the long previous use of the "sun in splendour" in European heraldry. It consists of a golden disc with a face from which rays emerge, alternating between flaming ones rotating clockwise and straight ones; in the Argentine case being 32 rays, while in the Uruguayan case it conforms to the convention of the European heraldry of 16 rays. However, the original lack of regulation regarding the sun's design led to a great variety of different styles over time, until they were definitively standardized by law in the mid-20th century.

The first official use of the sun as a national symbol was in 1813 with the Constituent Assembly of the United Provinces of the Río de la Plata, appearing on its seal (which would later become Argentina's national coat of arms) and on its first national coins. The sun was incorporated into the country's war flag in 1818, and this design gradually became the standard for representing the national state, while civilians were restricted to using the version without the sun. Throughout the rest of the 19th century, the sun appeared in numerous distinct designs on flags, notably in red during the government of Juan Manuel de Rosas, as well as on coins, with significant variations across each province. At the beginning of the 20th century, historical studies on the flag and coat of arms emerged, with proposals aimed at aligning the sun's design with that of the 1810s. However, it was not until 1944 that a definitive regulation was established, finalizing the design of the Sun of May based on the first national coins of 1813. Finally, in 1985, it was established that the only Argentine flag was the one with the sun, eliminating the obligation for civilians to use the sunless version.

In the case of Uruguay, it was constituted as a country in 1818 at the end of the Cisplatine War, which confronted the United Provinces of the Río de la Plata and the Empire of Brazil for the control of the Banda Oriental, and chose national symbols linked to those of Argentine independence. Similar to the Argentine case, the sun used in Uruguay's coat of arms and flag underwent numerous variations until its current design was formalized in 1952. This decree also standardized the color of the flag's stripes as blue, distinct from the light blue used in Argentina's flag.