In Season 1 of The Golden Girls, the main characters' ages were approximately:

• Rose Nylund: 55 years old
• Dorothy Zbornak: 53 to 55 years old
• Blanche Devereaux: About 53 years old
• Sophia Petrillo: 79 years old

These ages come from various clues and explicit mentions across the episodes, especially in the early seasons of the show. The actresses themselves were, for comparison, generally older than their characters, with Betty White (Rose) being 63, Bea Arthur (Dorothy) 63, Rue McClanahan (Blanche) 51, and Estelle Getty (Sophia) being 62 years old when the show started.