Bya: Difference between revisions
Marked out nonscientific infornation Tags: Reverted Mobile edit Mobile web edit |
Reverted 1 edit by 73.143.199.192 (talk): No |
||
| (13 intermediate revisions by 11 users not shown) | |||
| Line 1: | Line 1: | ||
{{Short description|Abbreviation for "billion years ago"}} |
|||
{{Other uses|BYA (disambiguation)}} |
{{Other uses|BYA (disambiguation)}} |
||
{{lowercase}} |
{{lowercase}} |
||
| ⚫ | '''bya''' or '''b.y.a.''' is an [[abbreviation]] for "'''[[1000000000 (number)|billion]] years ago'''". It is commonly used as a [[unit of time]] to denote length of time before the present in 10<SUP>9</SUP> years. This [[Acronym#Nomenclature|initialism]] is often used in the sciences of [[astronomy]], [[geology]], and [[paleontology]]. |
||
| ⚫ | The "billion" in bya is the 10<SUP>9</SUP> "billion" of the [[Long and short scales|short scale]] of the [[United States|U.S.]],<ref name="Gale2009">Gale, Joseph (2009). ''Astrobiology of Earth: The Emergence''. Oxford: Oxford University Press, p. [https://books.google.com/books?id=64zn0nxDVUYC&pg=PA21 21.]</ref> not the long-scale 10<SUP>12</SUP> "billion" of some [[Europe]]an usage. Billion by this convention (10<SUP>9</SUP>) is often called a "thousand million" in the UK and a "milliard" in some other countries.<ref>Chartrand, Mark (2004). ''Satellite Communications for the Nonspecialist''. New York: SPIE Press, p. [https://books.google.com/books?id=MM0d2cMUWbEC&pg=PA73 73.]</ref> For this reason, there is potential for some confusion, and some scientists prefer the unit Gya, while others prefer [[Giga-annum|Ga]] (Giga-annum), however, bya remains in more widespread use.<ref name="Gale2009"/> In 1974, the UK switched from the long scale to the short scale.<ref name="Gale2009"/> |
||
| ⚫ | '''bya''' or '''b.y.a.''' is an [[abbreviation]] for "'''[[1000000000 (number)|billion]] years ago |
||
| ⚫ | The "billion" in bya is the 10<SUP>9</SUP> "billion" of the [[Long and short scales|short scale]] of the [[United States|U.S.]],<ref name="Gale2009">Gale, Joseph (2009). ''Astrobiology of Earth: The Emergence''. Oxford: Oxford University Press, p. [https://books.google.com/books?id=64zn0nxDVUYC&pg=PA21 21.]</ref> not the long-scale 10<SUP>12</SUP> "billion" of some [[Europe]]an usage. Billion by this convention (10<SUP>9</SUP>) is often called a "thousand million" in the UK and a "milliard" in some other countries.<ref>Chartrand, Mark (2004). ''Satellite Communications for the Nonspecialist''. New York: SPIE Press, p. [https://books.google.com/books?id=MM0d2cMUWbEC&pg=PA73 73.]</ref> For this reason, there is potential for some confusion, and some scientists prefer the unit |
||
Related units are [[Mya (unit)|mya]] ("million years ago"), and '''byr''' ("billion years"). These are traditionally written in [[lowercase]]. [[Giga-annum|Ga]] or Gya has a [[capitalization|capitalized]] first letter instead. |
Related units are [[Mya (unit)|mya]] ("million years ago"), and '''byr''' ("billion years"). These are traditionally written in [[lowercase]]. [[Giga-annum|Ga]] or Gya has a [[capitalization|capitalized]] first letter instead. |
||
Latest revision as of 22:44, 9 August 2024
bya or b.y.a. is an abbreviation for "billion years ago". It is commonly used as a unit of time to denote length of time before the present in 109 years. This initialism is often used in the sciences of astronomy, geology, and paleontology.
The "billion" in bya is the 109 "billion" of the short scale of the U.S.,[1] not the long-scale 1012 "billion" of some European usage. Billion by this convention (109) is often called a "thousand million" in the UK and a "milliard" in some other countries.[2] For this reason, there is potential for some confusion, and some scientists prefer the unit Gya, while others prefer Ga (Giga-annum), however, bya remains in more widespread use.[1] In 1974, the UK switched from the long scale to the short scale.[1]
Related units are mya ("million years ago"), and byr ("billion years"). These are traditionally written in lowercase. Ga or Gya has a capitalized first letter instead.
See also
[edit]References
[edit]
 | This standards- or measurement-related article is a stub. You can help Wikipedia by expanding it. |
 | This time-related article is a stub. You can help Wikipedia by expanding it. |