Convert year to millennium

year

Definition: A year (symbol: y, yr, or a) is a measurement of time based on Earth's orbital period around the sun. This is approximated as 365 or 366 days in the Gregorian calendar. Earth's orbit around the sun is seen as the passing of seasons in which weather, daylight hours, vegetation, and soil fertility, among other things, change.

History/origin: Various definitions of a year have been used by different calendars throughout history. The most commonly used calendar for civil affairs today is the Gregorian calendar, a solar calendar which consists of 365 or 366 days, depending on whether or not the year is a leap year. In astronomy, many other definitions of the year exist, such as the sidereal, draconic, lunar, and Gaussian year, among others. The Gregorian calendar is a calendar that was reformed from the Julian calendar, which was a calendar that itself was reformed from the ancient Roman calendar.

Current use: The definition of a year based on the Gregorian calendar is used worldwide. In some cultures, lunisolar calendars are also used. In astronomy, many different definitions of the year are used, including the Julian year as a unit of time equal to 365.25 days based on the SI (International System of Units) base unit of seconds.

millennium

Definition: Millennium is a measure of time duration. For conversion purposes, its value is 31557600000 times the reference unit, second.