What is the major historical change which have occurred in astronomical concepts?

That's a really broad category, but one of the biggest changes was probably the invention of the telescope. Telescopes have allowed astronomers to observe the stars with increasing accuracy and eventually allowed them to prove that the Sun, no the Earth, was the center of the solar system. I would recommend researching Copernican and Ptolemic models of the universe to get a better idea of the two different interpretation of the structure of the universe and then you can maybe go from there. The biggest thing that telescopes helped prove years after Copernicus' time was interstellar parallax -- basically that the stars we see from Earth move back and forth rather than spinning around us, so you might want to look that up, too. :)