The seven-day week is such a common part of our lives that we rarely stop to think about where it came from or why each day is named the way it is. But the story behind the names of the days of the week is a combination of astronomy, mythology, and cultural evolution that dates back to thousands of years. Let’s dive into it!
Origin of the Seven-Day Week
The concept of a seven-day week goes beyond modern civilizations and has been influenced by multiple ancient cultures. It has its roots in ancient Mesopotamia, specifically with the Sumerians and Babylonians, who lived in what is now Iraq. These civilizations established a seven-day week structure as early as 2300 BCE (about 4000 years ago). They were skilled astronomers and noted that there were seven celestial bodies visible to the naked eye: the Sun, Moon, Mars, Mercury, Jupiter, Venus, and Saturn. These celestial objects became central to their cosmology and, eventually, to their timekeeping. Each day was associated with one of these bodies, a tradition that influenced more cultures later on.
The Babylonians divided the lunar month, which is roughly 29.5 days, into four segments of seven days each, rounding the cycle to 28 days for practical purposes. This division made the lunar month more manageable and may have contributed to the popularity of the seven-day cycle. This system eventually spread throughout the Middle East and influenced neighboring cultures.
The seven-day cycle also aligned with religious and spiritual beliefs. For example, in Jewish tradition, God created the world in six days and rested on the seventh. This seventh day, the Sabbath, became a foundation of Jewish religious life and contributed to the global spread of the seven-day week.
While the Babylonians laid the foundation, the names we use for the days of the week today are largely derived from Roman mythology and the Latin language. Although initially, the Romans used an eight-day week for civil purposes. They adopted the seven-day week and assigned each day to one of the seven classical planets, which were associated with Roman gods. These names were then passed into other European languages (such as, Germanic), thereafter being influenced by local culture, language, and mystical beliefs.
Let’s take a closer look at each day:
Sunday (Sun’s day): This day is dedicated to the Sun, representing light, life, and strength. In Latin, it was called “dies Solis,” or “day of the Sun.” As Christianity spread, some regions began to refer to it as “the Lord’s Day,” but the older pagan name persisted in many languages.
- Monday (Moon’s day): The Moon was associated with femininity, rhythm, and cycles. In Latin, it was “dies Lunae.” This directly evolved into “Monday” in English, “lundi” in French, and “lunes” in Spanish—all derived from the Moon goddess Luna.
- Tuesday (Tiw’s day / Mars’ day): This day was associated with Mars, the Roman god of war, known as “dies Martis” in Latin. When the names were adapted by the Germanic peoples, Mars was equated with Tiw (or Tyr), a Norse god of war, leading to the English name “Tuesday.”
The Germanic people were a group of tribes from Northern Europe. The Norse, Vikings, Goths were Germanic people, speaking a Germanic language.
- Wednesday (Woden’s day / Mercury’s day): The Latin name “dies Mercurii” honors Mercury, the messenger god. The Germanic equivalent was Woden (or Odin), a powerful and wise Norse god, giving us “Wednesday.”
- Thursday (Thor’s day / Jupiter’s day): The Latin “dies Iovis” was named after Jupiter, king of the gods. In Norse mythology, Thor was a similar thunder-wielding god, which is why we call it “Thursday.”
- Friday (Frigg’s day / Venus’ day): Venus, the goddess of love, was honored on “dies Veneris.” The Germanic peoples equated her with Frigg (or Freya), another goddess of love and beauty, leading to “Friday.”
- Saturday (Saturn’s day): Interestingly, Saturday is the only day that retains its original Roman name in English. “Dies Saturni” was named for Saturn, the god of agriculture and time.
Cultural Variations
While English and other Germanic languages use these mythologically inspired names, not all cultures follow this pattern. In many languages, the days are often simply numbered (e.g., “first day,” “second day,” etc.), with the Sabbath as the final day of rest.
Scientific and Astronomical Roots
The assignment of each day to a planet is not random but follows a complex system rooted in ancient astrology. According to the “planetary hours” system, each hour of the day was ruled by one of the seven classical planets, rotating in a specific order. The planet that ruled the first hour of a day also ruled the entire day. This pattern explains the specific ordering of the days and links back to Babylonian astrology.
The Legacy
Despite the rise of modern astronomy and the global adoption of the Gregorian calendar, the planetary and mythological roots of the week remain embedded in our daily lives. These ancient connections give us more than just a naming system; they show us how early humans viewed the cosmos.
Understanding how the days of the week were named reminds us that timekeeping is not just a scientific endeavor—it is also deeply associated with cultural and spiritual values. Each time we say “Monday” or “Friday,” we are unknowingly invoking gods, planets, and traditions that have been passed down for millennia. It’s a small but powerful example of how mythology and astronomy continue to shape our world, even in ways we might not always notice.
By Dr trishani biswas