Byr

The billion years or the Giga - year is a unit of time used in geology and astronomy. It is in the literature with Ga and in the English literature also often abbreviated Gyr.

Astronomical events such as the formation of a galaxy or sections of stellar evolution are expressed in Gyr. The age of the universe is in the present state of science, according to the standard model of cosmology, about 13 Ga, the age of our solar system about 4.6 Ga.

A distinction of the year billion, which means a period of time, Gya is for English Giga -years ago ( Bya or for billion years ago) in the historical geology of the name for a moment. For example, 4.6 Gya the beginning of the Hadaikums on earth is recognized - that is 4.6 billion years before the geological time now - and this geological epoch lasted about 0.6 Ga.