Millennium (ka) - Unit Information & Conversion
What is a Millennium?
Definition
A millennium is a unit of time equal to 1000 consecutive years. It is used to denote very long periods, particularly in historical, geological, and cosmological contexts.
History
The word "millennium" comes from the Latin words "mille" (thousand) and "annus" (year). Its use became prominent with the adoption of the Anno Domini (AD) calendar system, particularly around the year 1000 AD and later around 2000 AD, sparking discussions about the start and end of millennia based on calendar counting.
Common Uses
Millennia are used for:
- Historical Epochs: Dividing history into large blocks (e.g., the 1st millennium AD, the 3rd millennium BC).
- Geological Time Scales: Discussing events over thousands of years in geology, paleontology, and archaeology.
- Long-Term Planning: Referring to very long-term societal, environmental, or astronomical projections.
- Religious/Eschatological Contexts: Many religions have concepts related to millennial periods, prophecies, or cycles.
- Cultural Milestones: Marking significant thousand-year anniversaries or transitions.
Unit FAQs
How many years are in one millennium?
A millennium consists of exactly 1000 years.
When did the 3rd millennium begin?
Following the standard convention where centuries and millennia start with year '01 (because the calendar started at 1 AD, not 0), the 3rd millennium AD began on January 1, 2001, and will end on December 31, 3000.
Is the millennium an SI unit?
No, the millennium is not part of the International System of Units (SI). The base SI unit for time is the second. For very long timescales, scientists often use years (like Julian years for consistency) or multiples such as kiloyears (kyr, often represented as 'ka' for kiloannum), megayears (Myr), or gigayears (Gyr).
Millennium Conversion Formulas
To Second:
To Minute:
To Hour:
To Day:
To Week:
To Month:
To Year:
To Millisecond:
To Microsecond:
To Nanosecond:
To Decade:
To Century:
To Fortnight:
To Planck Time:
To Shake:
To Sidereal Day:
To Sidereal Year:
Convert Millennium
Need to convert Millennium to other time units? Use our conversion tool.