Cosmology is the science of the Universe as a whole.
We live in a scientific age in which new knowledge is generated by observation and careful deduction.
Cosmology is now a very active branch of science, which draws upon the principles of mathematics and physics as applied to astronomical and astrophysical observations.
The scientific age began four centuries ago, when scientists such as Galileo Galilei, realized that the way to knowledge and understanding must be based upon observations of Nature and demonstrated facts rather than upon a dogma or intellectual construct.
Prior to the development of the scientific method, philosophers sifted through facts and observations keeping those that matched their theory and rejecting those that didnít.
The astronomers of Ancient Greece put the Earth firmly at the center of the Universe because that fit their principles of physics and preconceived ideas that the stars could not be so big and far away.
In the 16th century, Nicolas Copernicus, a Polish monk, put forward the idea that the planets and the Earth orbit the Sun. This concept was in direct conflict with the teachings of the Church, which held that the Earth was the center of the Universe and that Heaven was beyond the Celestial Spheres for the planets. Copernicus's heliocentric model of he Universe never obtained support from the Chuch during his lifetime. He died in 1543, unaware that he had sown the seeds for a revolution initiated by Galileo that laid the foundations for the scientific age and a systematic evolution in our view of the Universe.
Galileo is the architect of moder science because set up the concepts and the principles of careful observations (and experimentation) to find out from Nature as well as reason. He developed the Scientific Method. He built a telescope powerful enough to study the moon and planets and he his his observations to demonstrate that the Copernican model is corrrect. He then publicized his results.
Cosmologists today have equipment and resources that Galileo could not have imagined. Nevertheless, the Scientific Method developed by Galileo and others continues to be the guiding principle and approach for scientists of all disciplines.
Cosmologists develop and use extremely sophisticated scientific instruments and high-power telescopes to observer the most distant objects known. They use powerful computers and alogrithms to process and analyze their observations. They work on very complicated mathematical theories to make predictions to test their theories. They study the nature of matter on a scale which is incredibly small as they strive to understand the origins of the Universe. Cosmology in the scientific age is a highly specialized branch of science, which has the primary aim of answering fundamental questions about the Universe.
Cosmologist are perhaps more aware than most scientists of the need to make their work accessable and understandable to non-scientists as well as to scientists in other disciplines. Te big questions of cosmology are of great interest to people from all walks of life.
For example
If it is finite, how big is it?
Is the Universe curved? (open, flat, or closed?) News Story about Flatness of Universe
And raised more questions as our ignorance is illuminated to the point we have a good idea of the large scale picture of cosmology.