Good digging!
https://en.wikipedia.org/wiki/Sun_of_May
The Sun of May is a figurative sun that represents * ‘Sol Invictus’ (”Unconquered Sun” or “unconquered”) “a Roman mythological god identified with the Sun (the solar deity in the ancient Roman religion).
... A legend claims that as the new government was proclaimed, the sun broke through the clouds, which was seen as a good omen.
Sol Invictus appears on the Argentinian national flag.