For a long time sushestvovalo opinion that the Earth is the main and largest body in the Universe and around her all heavenly bodies revolve. It was believed that our planet is the center of the Universe. It was followed by the spheres of the Sun and planets, then located the fixed stars. And even further - mover, start, guided by God and the leading of the celestial sphere in motion. This world was proposed by the Greek astronomer Ptolemy in the 2nd century BC and was called the geocentric theory, or system of Ptolemy, which lasted for many centuries.
The system of Ptolemy was questioned only in 1543. Polish mathematician and astronomer Nicolaus Copernicus (1473-1543) for more than 30 years he developed the idea of a heliocentric world picture (from the Greek "Helios" - Sun), according to which the Earth is an ordinary planet, among others revolving around the Sun.
Ideas of Copernicus were only a hypothesis, not proven facts. At that time astronomy had no instruments capable of observing celestial bodies out of sight. This became possible when the Italian scientist Galileo Galilei (1564-1642) has created a magnifying pipe of his own design and sent it into the sky, at the end of 1609. Pipe Galilee, according to today's views, was very weak - increased only 30 times. But discoveries made with it, knocked over all pre-existing people have ideas about the world, its size and the device!
It turned out that the universe has a huge scale. The milky way was split into countless stars. On the moon were seen mountains, valleys, "the sea". This meant that the heavens consist of the same material objects, like the Earth. Venus was found to change the visible phases. She has gained a view of the narrow Crescent, full disk, which pointed to its revolution around the Sun and not around the Earth.
A few months collapsed all the medieval picture of the world. His contemporaries called Italian scientist "Columbus Universe".