The million year is a unit of time often used in astronomy and geology of a million years. It is in German with million years or very rarely with Jmio. abbreviated. In the specialist literature, based on the SI units , the abbreviation Ma (Megaannum) can also be found. Accordingly, there is also Ga (Gigaannum) for a billion years , the abbreviation ka for a thousand years is rarely used.
The galactic year , i.e. the orbit of the solar system around the center of the Milky Way, is estimated to have a period of approx. 225 Ma. The Carboniferous geochronological period , during which most of the coal was formed, lasted 60 Ma.