In general, Aeronomy is the science that studies all planetary atmospheres in which physical and chemical processes, resulting from the dissociation and ionization phenomena under the influence of the solar radiation, are important.
This word became official in 1954 when the International Union of Geodesy and Geophysics (IUGG) adopted it. It refers to the scientific study of the upper atmospheric regions of the Earth and other solar system bodies.
It also includes the studies of aurora, airglow, the ionosphere, Van Allen radiation belts, cosmic rays, and radiative and photochemical phenomena. ISRO has taken initiatives for feasibility studies on missions to Venus as well as Aeronomy studies.