Initially, the heavens were depicted as very similar to the earthly world.
Daily observations also showed that the earth is still and there can be nothing but the earthly world.
Day in and day out, year out, a man was convinced by experience that the Sun, Moon, planets, and stars move in the sky, rise in the east and set in the west.
Historians of the ancient world say that the level achieved by ancient astronomy was very high. This is true. But it is impossible to forget that astronomy at that time was a purely descriptive science, powerless to oppose anything to religious ideas about the structure of the world. The real nature of the phenomena it studied was completely hidden from it.
Therefore, the ancient thoughts about the nature of heaven were based mainly on speculation, grew into fantastic, often religious images.
Ancient Greek mathematician Pythagoras (VI century BC), who traveled a lot, was the first to express the idea of the sphericity of the Earth. Philosopher Aristotle (IV century B.C.) proved that the Earth is a ball, because in the southern countries in the sky there are new constellations, invisible in the north, and the farther we move to the north, the more appears in the sky of the stars not entering.
Gradually, the idea that the Earth is a sphere hanging in space and not based on anything was spreading among ancient thinkers.
So step by step people moved to unravel the mystery of the universe. However, in this way, they had two serious obstacles. Firstly, people did not have the necessary devices to observe celestial bodies. Secondly, the successes of ancient science were for many centuries suspended by the establishment of Christianity.
Still in ancient Greek philosophy, there was a current that sharply contrasted heavenly and terrestrial. While the great materialist of antiquity Democritus (V - IV century BC) debunked the faith in the gods and denied the divinity of the heavenly luminaries, Plato (V - IV century BC) philosopher-idealist, said that astronomy is studying in the sky an ideal world corresponding to the merits of the gods living there. Everything heavenly, according to Plato's teachings, is eternal and invariable. This representation was also supported by Plato's student Aristotle. He believed that the earthly world consists of four elements - fire, air, water, and earth.
The representations of Plato and Aristotle had a strong influence on the picture of the world, created by the Greek astronomer Ptolemy in the II century BC. Ptolemy tried to explain the visible movements in the sky of the planets of the solar system - Venus, Mars, Jupiter, Saturn. Ptolemy believed that the Earth is in the center of the world and can not move. Therefore he has thought up the difficult scheme according to which the Sun appears on third place from the Earth, and all planets move not only around the Earth but also on the additional orbits explaining visible ways of planets in the terrestrial sky.
Ptolemy's system has become a basis of Christian cosmology. Under the doctrine of the Christian church, the person - tsar of nature. For his sake, the Earth and the Sun, heavens, and underworld are created.
So the heavens looked like during many years of domination of Christian belief.
The considered stages of human representations about the Earth and the Universe were, thus, a mix of observations and conjectures. The heavenly world was therefore built either by direct analogy with the earthly or in direct opposition to it.
But science cannot rely only on common sense, limited to the framework of everyday routine. It asserts that the world is infinite in its scale and properties and that what turns out to be undoubtedly correct in the world around the man is inapplicable in the world of tiny particles of matter - molecules and atoms or in the world of infinitely large cosmic bodies - stars and galaxies. Observation and experience, scientific experiments, and, ultimately, social and industrial practice are the only true means of distinguishing truth from error, scientists say. Only these means can confirm or disprove the bold assumptions of the human mind.
Ptolemy's system was questioned by the Polish mathematician and astronomer Nikolai Copernicus (1473-1543). Outstanding thinker, Nikolai Copernicus for more than 30 years developed the idea of a heliocentric picture of the world (from the Greek "helios" - the sun), according to which the Earth is an ordinary planet, among others, circulating around the central luminary - the Sun. Copernicus firmly rejected the former prejudices that the Earth is the center of the world and the center of gravity around which all the celestial bodies should move.
Copernicus proved that the universe does not move around the stationary Earth, and, conversely, the Earth moves in outer space.
But Copernicus' ideas were initially only a hypothesis that was not proven by the facts. In fact, in the XVI century astronomy did not possess the devices capable to help the person to comprehend the nature of heavenly bodies. All known then astronomical tools had value for observant astronomy, helped to study visible movements and position of stars and planets in the sky. These observations, in the end, also played a role in creating a true picture of the world, but they could not tell people about the structure, size of celestial bodies and the scale of the universe.