Гигагод(кратная году единица измерения времени, равная миллиарду лет. Применяется преимущественно в космологии, а также в геологии и в науках, связанных с изучением истории Земли. Vicomte)
миллиард лет(A billion years or giga-annum (109 years) is a unit of time on the petasecond scale, more precisely equal to 3.16×1016 seconds (or simply 1,000,000,000 years). The terms are used in geology, paleontology, geophysics, astronomy, and physical cosmology. Byr was formerly used in English-language geology and astronomy as a unit of one billion years. Subsequently, the term gigaannum (Ga) has increased in usage, with Gy or Gyr still sometimes used in English-language works (at the risk of confusion with Gy as abbreviation for the gray, a unit of radiation exposure). Astronomers use Gyr or Gy (or Ga, where the a stands for annum, Latin for "year") as the symbol for gigayear. wikipedia.orgLyuFi)
wikipedia.org LyuFi)