Convert Week (week) to Year (Sidereal) (y (sidereal)) instantly.
About these units
Week (week)
A week consists of seven days, a structure stemming from ancient Babylonian and Near Eastern traditions that associated each day with a celestial body (Sun, Moon, and five visible planets). The seven-day week spread through Judaism, Christianity, and Islam, becoming one of the world's most persistent cultural time cycles. Unlike the day, month, or year, the week has no astronomical basis—its endurance is purely cultural. Yet it organizes labor systems, religious observances, markets, and global business schedules. The survival of the week across millennia demonstrates the remarkable staying power of cultural tradition, transcending scientific revolutions, political changes, and the rise of international standardization.
Year (Sidereal) (y (sidereal))
A sidereal year is the time it takes Earth to complete one full orbit relative to distant fixed stars, lasting approximately 365.25636 days. This is the "true" orbital period of Earth in space, unaffected by precession-related shifts of the equinoxes. Sidereal years are used in celestial mechanics, spacecraft navigation, and modeling solar system dynamics. The slight difference between the tropical and sidereal year (about 20 minutes) reveals how Earth's wobbling axis alters how we perceive time, creating two distinct astronomical year definitions.