You probably have heard the word “Universe” more than once. What it is? This word usually means outer space and everything that fills it: cosmic, or celestial, bodies, gas, dust. In other words, this is the whole world. Our planet is a part of the immense Universe, one of countless celestial bodies.
For thousands of years, people admired the starry sky, watching the movement of the Sun, the Moon and the planets. And they always asked themselves an exciting question: how is the Universe arranged?
Modern ideas about the structure of the universe evolved gradually. In ancient times, they were not at all the same as now. For a long time, the center of the universe was considered the Earth.
The ancient Indians believed that the Earth was flat and rested on the backs of giant elephants, which, in turn, rest on a tortoise. A huge turtle stands on a snake, which personifies the sky and as it closes the terrestrial space.
The Universe was seen by other peoples living on the banks of the Tigris and Euphrates rivers. The land, in their opinion, is a mountain that is surrounded on all sides by the sea. Above them in the form of an overturned bowl is located the starry sky.
Ancient Greek scientists made a lot for the development of views on the structure of the Universe. One of them, the great mathematician Pythagoras (about 580-500 BC), is the first to assume that the Earth is not at all flat, but has the shape of a ball. The correctness of this assumption was proved by another great Greek, Aristotle (384-322 BC. E.
Aristotle proposed his model of the structure of the universe, or the system of the world. In the center of the Universe, according to the scientist, there is a stationary Earth, around which eight celestial spheres, solid and transparent (in translation from the Greek “sphere” – a sphere) rotate. Celestial bodies — planets, the moon, the sun, and stars — are fixed on them. The ninth sphere provides the movement of all other spheres, it is the engine of the Universe.
Aristotle’s views were firmly established in science, although even some of his contemporaries did not agree with him. The ancient Greek scientist Aristarkh Sammosky (320-250 BC) believed that the center of the universe was not the Earth, but the Sun; Earth and other planets move around it. Unfortunately, these brilliant guesses were rejected and forgotten at that time.
The views of Aristotle and many other scientists were developed by the greatest ancient Greek astronomer Claudius Ptolemy (c. 90-160 AD). He developed his system of the world, in the center of which, like Aristotle, placed the Earth. According to Ptolemy, the Moon, the Sun, five (known at that time) planets, and also the “sphere of fixed stars” move around the motionless spherical Earth. This sphere limits the space of the Universe. Ptolemy detailed his views in detail in the grand work “The Great Mathematical Construction of Astronomy” in 13 books.
The Ptolemy system well explained the apparent motion of celestial bodies. She allowed to determine and predict their location at one time or another. This system dominated science for 13 centuries, and the book of Ptolemy was a table for many generations of astronomers.
Two great greeks
Aristotle is the greatest scholar of ancient Greece. He was originally from the city of Stagira. Throughout his life, he devoted the collection and understanding of information known to scientists of his time. He was interested in everything: the behavior and structure of animals, the laws of motion of bodies, the structure of the universe, poetry, politics. He was the teacher of the outstanding commander Alexander the Great, who, having achieved fame, did not forget his old teacher. From his military campaigns, he constantly sent him samples of plants and animals unknown to the Greeks. After himself, Aristotle left numerous works, for example, “Physics” in 8 books, “On parts of animals” in 10 books. The authority of Aristotle for many centuries was indisputable in science.
Claudius Ptolemy was born in Egypt, in the town of Ptolemais, and then studied and worked in Alexandria, a city founded by Alexander the Great. It was the largest city in the Mediterranean, the capital of the Egyptian kingdom. In his libraries were collected scientific writings from the countries of the East and Greece. Only in the famous museum of Alexandria more than 700 thousand manuscripts were kept. Here worked well-known scientists of the ancient world. Ptolemy was a well-educated man: he studied astronomy, geography, and mathematics. Summarizing the work of ancient Greek astronomers, he created his own system of the world.
The universe is outer space and everything that fills it: celestial bodies, gas, dust. Modern ideas about the structure of the universe evolved gradually. For a long time, Earth was considered its center. It was precisely this point of view that the ancient Greek scientists Aristotle and Ptolemy, who created their systems of the world, adhered to.