Cosmology is defined as the study of the origin, purpose, structure and functioning of the universe. Vedic cosmology gives a vast amount of information about not only the structure of the phenomenal universe as we see it, but also a clear idea of the source of the manifested universe, its purpose, and the subtle laws that govern its operation.
The fundamental concept that pervades Vedic cosmology is the relation and dependence that everything has upon the Supreme Personality of Godhead, Sri Krishna; the source of creation, maintenance and dissolution of the manifested worlds. Although Sri Krishna is the ultimate cause of all other causes, His existence is beyond the material energy and He Himself takes no direct part in these activities, but indirectly controls the universe through his delegated expansions and empowered agents in the form of various incarnations and demigods.
Pervading the entire science of Vedic cosmology is the understanding that the universe is created and maintained by personal activity. This means that behind all apparently mechanistic laws and events there is one or more persons who enact and administer the laws, and control all universal events.
Accepting a Supreme controller is central to entering into an understanding of Vedic cosmology. As such, proper comprehension of the subject requires that one first accept that as human beings we have very limited sensual faculties with which to examine the universe, meaning that we can never gain a complete picture of the universe by our own sensual and intellectual faculties alone.
From the Vedas and especially the Vedic cosmology, we can receive information from beyond our sensory plane or awareness, that describes the hierarchy of beings within the universe, leading ultimately to the Supreme Personality of Godhead, Sri Krishna. Most importantly, we get information of how we can successfully interact with the universe to live a peaceful and progressive life in this world, while gradually elevating our consciousness to the spiritual plane.
As Krsna states in the Bhagavad-gita,
A person in full consciousness of Me, knowing Me to be the ultimate beneficiary of all sacrifices and austerities, the Supreme Lord of all planets and demigods, and the benefactor and well-wisher of all living entities, attains peace from the pangs of material miseries.
from Bhagavad Gita 5.29
Thus, human society can take the greatest benefit from appreciating and understanding this instruction and molding their life around it. As such, Vedic cosmology is not merely an attempt to understand the world around us, rather it is the process by which we understand both the world, our place within it, and the relationship between ourselves, this world and the Supreme source of all, from Whom all other energies are emanating.