Who discovered Sunday?

Sunday, as a day of the week, was named after the Sun, derived from Latin "dies Solis." The concept of a seven-day week has roots in ancient civilizations, including the Babylonians, who are credited with its development around the 6th century BCE. The designation of Sunday as a day of rest and worship became prominent in Christian tradition, but it wasn’t "discovered" by a single individual; rather, it evolved over time through cultural and religious practices.