Sosigenes

Sosigenes was the royal astronomer and mathematician who helped Julius Caesar devise a better calendar. He confronted the stubborn problem of fitting solar and lunar cycles into an orderly year, then proposed months of different lengths and an extra day in February every fourth year. His solution produced a 365-day calendar with periodic leap years and placed January 1 at the year's beginning. Caesar initially doubted the plan, so Sosigenes appealed to imperial ambition by imagining profits from instruction manuals and future calendar problems. Knowledgeable, patient, and comically forward-looking, Sosigenes turned complicated calculations into a system ordinary people could follow. His work gave Caesar's reform the structure needed to keep the seasons and the calendar from drifting apart.