Millennium (mil)
The millennium is one thousand years, or approximately 31,557,600,000 seconds based on the Gregorian average year. It is the timescale of civilizations, of ice ages and interglacials, and of the rise and fall of languages. A single millennium encompasses the span from the fall of the Western Roman Empire to the Renaissance, or from the first European contact with the Americas to the present day. The millennium is too long to be meaningful in everyday life but is indispensable in archaeology, geology, climate science, and any field that grapples with the deep history of the Earth and its people.
Definition
One millennium equals exactly 1,000 years, 100 centuries, 10,000 decades, or approximately 365,242.5 days. In seconds, using the Gregorian average year, one millennium equals 31,557,600,000 seconds. In scientific notation, one millennium equals approximately 3.156 × 10¹⁰ seconds.
History
The word millennium comes from the Latin mille, thousand, and annus, year, and entered the English language in the seventeenth century. The concept of a thousand-year period carries deep religious significance in Christianity: the Book of Revelation describes a thousand-year reign of Christ, giving the word millenarianism to describe any belief in a coming age of perfection. The passage from the first to the second millennium CE, around the year 1000, prompted widespread apocalyptic expectation in medieval Europe, though historians debate how widespread this was. The passage from the second to the third millennium, on January 1, 2000, brought the Y2K computer crisis, the largest global infrastructure preparedness effort in history, and the largest single calendar celebration humanity has ever organized.
Common Uses
In archaeology, the millennium is a standard unit of reference: the Bronze Age began roughly 5 millennia ago, writing was invented about 5 millennia ago, and the first cities emerged between 5 and 6 millennia ago. In climate science, ice core records extend across dozens of millennia, revealing cycles of glaciation and warming. In geology and paleontology, millennia are a fine-scale unit compared to the millions of years used to describe major evolutionary transitions. In linguistics, language families are traced back over one to several millennia: Proto-Germanic, the ancestor of English, German, Dutch, and the Scandinavian languages, was spoken roughly 2 millennia ago.
Did You Know? Facts About Millennium
- The year 2000 CE was celebrated globally as the dawn of the third millennium, but by strict calendar reckoning, the third millennium began on January 1, 2001. The astronomical excitement of round numbers proved stronger than calendar accuracy, and most of the world celebrated a year early.
- In the scientific literature, particularly in climate and Earth science, millennia are often expressed as 'ka BP' (kilo-annum before present), where 'present' is conventionally defined as 1950 CE. The last ice age peaked around 20 ka BP, and the Holocene — the current warm period — began about 11.7 ka BP.
- The Roman Empire in the West lasted from its traditional founding in 753 BCE to its fall in 476 CE, spanning roughly 1.2 millennia. The Eastern Roman Empire (Byzantine Empire) continued for nearly another millennium, falling in 1453 CE.
- The Voyager 1 spacecraft, launched in 1977, will not come within two light-years of another star for roughly 40,000 years, or 40 millennia. In geological terms, this is a very short time — the Grand Canyon took about 5 to 6 million years to form.
- Languages change so profoundly over millennia that a speaker of modern English would be completely unable to understand Old English from a thousand years ago. English, German, French, Spanish, Russian, Hindi, and dozens of other languages all descend from a common ancestor spoken about 5 to 6 millennia ago.