Byr

（重定向自Gigayear）

A gigaannum or gigayear (Byr, Gyr or Gy) is a period of one billion years (10 or 1,000,000,000 years). Retrospect time periods may be expressed as X billion years ago (bya). The prefix giga- is preferred to billion- to avoid confusion in the long and short scales over the meaning of billion; the postfix annum may be further qualified for precision as a sidereal year or Julian year.

单词	Gigayear
释义	Gigayear 英语百科 Byr （重定向自Gigayear） A gigaannum or gigayear (Byr, Gyr or Gy) is a period of one billion years (10 or 1,000,000,000 years). Retrospect time periods may be expressed as X billion years ago (bya). The prefix giga- is preferred to billion- to avoid confusion in the long and short scales over the meaning of billion; the postfix annum may be further qualified for precision as a sidereal year or Julian year.
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