Names of the days of the week

In a vast number of languages, the names given to the seven days of the <a href="/facts/Week/KJjQTKIh">week</a> are derived from the names of the <a href="/facts/Classical_planet/wBq07pNt">classical planets</a> in <a href="/facts/Hellenistic_astronomy/ehwqftGz">Hellenistic astronomy</a>, which were in turn named after contemporary deities, a system introduced by the <a href="/facts/Sumer/bxRz093q">Sumerians</a> and later adopted by the <a href="/facts/Babylonia/J4jjdUua">Babylonians</a> from whom the <a href="/facts/Roman_Empire/l4E1aUuV">Roman Empire</a> adopted the system during <a href="/facts/Late_antiquity/sPTl0dyD">late antiquity</a>. In some other languages, the days are named after corresponding deities of the regional culture, beginning either with <a href="/facts/Sunday/lUmoQM0d">Sunday</a> or with <a href="/facts/Monday/QK6BbmH4">Monday</a>. The <a href="/facts/Seven-day_week/KJjQTKIh">seven-day week</a> was adopted in early Christianity from the <a href="/facts/Hebrew_calendar/s5XBFz4h">Hebrew calendar</a>, and gradually replaced the Roman <a href="/facts/Internundinum/cleohoCf">internundinum</a>.
Sunday remained the first day of the week, being considered the day of the sun god <a href="/facts/Sol_Invictus/VaGty2lG">Sol Invictus</a> and the <a href="/facts/Lord%27s_Day/A7nl284w">Lord's Day</a>, while the Jewish <a href="/facts/Sabbath/bdPkL8Dw">Sabbath</a> remained the seventh.
The Babylonians invented the actual seven-day week in 600 BCE, with Emperor Constantine making the Day of the Sun (dies Solis, "Sunday") a legal holiday centuries later.
In the international standard <a href="/facts/ISO_8601/4N8kykG9">ISO 8601</a>, Monday is treated as the first day of the week, but in many countries it is counted as the second day of the week.

Names of the days of the week open-in-new

Names of the days of the week