The study of the processes that influence the amount, composition, and distribution of chemical compounds and isotopes in geologic environments is known as geochemistry. This field of Earth Science uses chemical concepts to gain a better knowledge of the Earth's and other planets' systems. Geochemists believe that the Earth is made up of separate spheres – rocks, fluids, gases, and biological — that exchange mass and energy over time. The basis for studying the co-evolution of the solid Earth, its oceans, atmosphere, biosphere, and climate is an understanding of reaction rates and the spectrum of physical variables responsible for chemical expressions of each sphere. The study of chemical transformations of biological components in rocks, as well as the cyclic flow of individual elements (and their compounds) between living and nonliving systems are all part of modern geochemical research. Certain areas of geochemical research, such as the origin and relative abundance of elements in the solar system, the Milky Way Galaxy, and the universe as a whole; the chemical composition of meteorites; and the ages of terrestrial and lunar rocks, have become intertwined with cosmology since the 1960s.