Issued by the Central African Republic in 1964, this 25 F stamp commemorates the Année Internationale du Soleil Calme (International Year of the Quiet Sun) held from 1964 to 1965. The design, by Durrens Frères, elegantly combines scientific symbolism with natural motifs—leaves intertwined with a stylized red sun representing solar study during minimal sunspot activity. This issue highlights global cooperation in solar and atmospheric research during a period of calm solar activity. A fine thematic piece for collectors interested in astronomy, science, and United Nations–related philately.