Is this a correct explanatory paragraph?

Cosmology is the study of the development of the Universe and how it is shaped. This area of research had originated from the works of Greek and Islamic astronomers during ancient times (Hetherington and McCray). They used elaborate tools and mathematical methods in order to investigate the heavens. However, the work of Nicolas Copernicus, who proposed the heliocentric model of the solar system, firmly established cosmology as a valid scientific field. In addition, the notable works of Galileo, Kepler, Hawking, and Hubble had resulted in the further advancement of the field. One of the main areas of exploration in cosmology is the beginning of the Universe, which is referred to as the Big Bang. It describes how the Universe formed from a single point that had exploded, which resulted in the formation of galaxies and all other structures (Hetherington and McCray). Furthermore, it continues with the notion that the Universe will continually expand in all directions from that single point (Hetherington and McCray). Cosmology can also explain the death of the Universe, and one idea is that there will be no free energy left to sustain complex processes in the distant future (Birkedal-Hansen). Cosmology had many contributors throughout history and it can explain the evolution of the Universe over time.

Hetherington S., Norriss, and W. Patrick McCray. Cosmic Journey: A History of Scientific Cosmology. American Institute of Physics. n.d. Web. 7 Oct. 2011.

Birkedal-Hansen, Andreas. PhysLink.com. PhysLink, n.d. Web. 7 Oct 2011.