'' Logic will get you from A to B. Imagination will take you every where?''~Albert Einstein
Before starting, first of all I would like to thank the astronomers who had started to think about outer space and ask the questions: What is the universe?, What is earth?, What does it look like?, Is it the center of the universe?, etc. Whatever has been discovered to date was because of them. Famous astronomers such as Copernicus, Aryabhatta, Galileo, etc. haven't followed the crowd. They followed their imagination, and their dreams. Their discoveries helped a lot. Their discoveries gave direction to our thoughts and imagination. Today, we know a lot about the universe. Today we can think about another planet (MARS). But there are many things left to know. It might be possible that we only know 10% of the universe, or we know more than 50% of the universe or we are on the last stage. Anything can possible. We should also appreciate those who are currently working on it. Following their passion. Space is for everyone.
The first person who dared to imagine beyond this world was Aristotle (384BC-322BC). He was an ancient greek philosopher and scientist. He had interest in many fields like Physics, Biology, Zoology, Metaphysics, Logic, Politics. He also had great interest in astronomy. According to him, the sun, the planets, and other stars travel in a separate spheres. He proved that the Earth is spherical instead of flat. He was the first to believe the Earth is the center of the universe.
Later, following his way, Ptolemy also believed the Earth was the center of the universe. Ptolemy(100AD-170AD) was an astronomer, mathematician, geographer, astrologer. He wrote several treatises, three of which were important. The first was the astronomical treatise. The second was geography and the last was the astrological treatise. He had major interest in astronomy. He is known for providing a useful tool for astronomical calculation to compute the position of the sun, the moon, the planets, and eclipses of the sun and moon. His astronomical treatise contains a star catalogue, which is a version of a catalogue created by Hipparchus. It is a list of forty eight constellation.
On the other hand, one legend was working on mathematics. Aryabhatta (476CE-550CE) was an Indian mathematician-astronomer. He had his major discoveries in mathematics. He discovered ZERO'0' and even showed the value of Pi'3.1416'. Not only in mathematics, he also had his major interest on astronomy. He was the one who believed that the earth rotates around the sun in elliptical path rather than circular. He claimed that the moon and planets shine by reflected sunlight. His major discoveries are remarkable in history.
After a long time, Copernicus was the one who took a major interest in astronomy. Nicolaus Copernicus (19 Feb 1473 - 24 May 1543) was an astronomer and a mathematician. He also had an interest in economics, medicine, and politics. He formulated a model of the universe known as Heliocentrism in which the sun is the center of the universe rather then the Earth.
Later the two astronomers - the German, Johannes Kepler (27 Dec. 1571 - 15 Nov. 1630) and Italian, Galileo Galilei (15 Feb. 1564 - 8 Jan. 1642) - started to publicly support Copernicus's theory. Galileo invented a telescope and started observing the night sky where he found several small satellites or moons revolving around Jupiter. He stated that everything did not have to orbit directly around the earth as Aristotle and Ptolemy had thought.
On the other hand, at the same time, Kepler had modified Copernicus's theory, showing that the planets moved not in circles, but in ellipses.
There were many astronomers who worked hard such as Plato, Hipparchus, etc. All the astronomers had one thing in common: They had many doubters and haters rather than friends. Still they never lost their hope. They followed their passion and imagination.