Kyr
Encyclopedia
The symbol kyr was formerly common in some English-language works, especially in geology
and astronomy
, for the unit of one thousand years or millennium
. The "k" is the unit prefix
for kilo- or thousand with the suffix "yr" simply an abbreviation for "year".
Occasionally, the "k" is shown in upper case, as in "100 Kyr"; this is an incorrect usage. "kyr" itself is often considered incorrect, with some preferring to use "ky"
Modern, ISO 31-1
recommended usage is ka for kiloannum, which avoids the implicit English bias of "year" by using a Latin
root.
Geology
Geology is the science comprising the study of solid Earth, the rocks of which it is composed, and the processes by which it evolves. Geology gives insight into the history of the Earth, as it provides the primary evidence for plate tectonics, the evolutionary history of life, and past climates...
and astronomy
Astronomy
Astronomy is a natural science that deals with the study of celestial objects and phenomena that originate outside the atmosphere of Earth...
, for the unit of one thousand years or millennium
Millennium
A millennium is a period of time equal to one thousand years —from the Latin phrase , thousand, and , year—often but not necessarily related numerically to a particular dating system....
. The "k" is the unit prefix
SI prefix
The International System of Units specifies a set of unit prefixes known as SI prefixes or metric prefixes. An SI prefix is a name that precedes a basic unit of measure to indicate a decadic multiple or fraction of the unit. Each prefix has a unique symbol that is prepended to the unit symbol...
for kilo- or thousand with the suffix "yr" simply an abbreviation for "year".
Occasionally, the "k" is shown in upper case, as in "100 Kyr"; this is an incorrect usage. "kyr" itself is often considered incorrect, with some preferring to use "ky"
Modern, ISO 31-1
ISO 31-1
ISO 31-1 is the part of international standard ISO 31 that defines names and symbols for quantities and units related to space and time.Its definitions include:Annex A of ISO 31-1 lists units of space and time based on the foot, pound and second...
recommended usage is ka for kiloannum, which avoids the implicit English bias of "year" by using a Latin
Latin
Latin is an Italic language originally spoken in Latium and Ancient Rome. It, along with most European languages, is a descendant of the ancient Proto-Indo-European language. Although it is considered a dead language, a number of scholars and members of the Christian clergy speak it fluently, and...
root.