What celestial bodies are called the planets of the solar system?
From time immemorial, people watched the nightsky and noticed that in addition to fixed objects, there are also those who change their position relative to the rest. Usually we say that these are stars, but is it so? What celestial bodies are called planets and what criteria should an object possess so that it can be called a planet? Which of them are part of the solar system?
Any object that does not emit light, heat, andexceeds a few meters in its size, is considered a planet ("wandering" - in translation from the Greek language). In the second half of the last century, more precise definitions were gradually introduced, and to date, so that the heavenly body is recognized as a planet, it must correspond to the following four conditions:
- The object should not be a star.
- Near the orbit of the object, other large celestial bodies should not move.
- The object should be a shape that is close to spherical.
- The object should rotate around the star.
Planet and star. What is the difference?
With the question of what heavenly bodies are calledplanets, we figured out, but what is the difference between them and the stars? The planet under the power of its own gravity is able to take a rounded shape and has a high density. But this mass is not enough for the thermonuclear reactions inside the body to begin. The star is a celestial natural body that can launch the thermonuclear reactions of helium, hydrogen and other gases, of which it consists, while radiating into space an incredible amount of energy converted into light, heat and electromagnetic fluxes.
The solar system and its constituent planets
According to modern science claims, whichcalled "astronomy," the planets of the solar system began to form about 4.5 billion years ago, becoming the consequence of a powerful explosion of one or several giant supernovae. The solar system was originally a gas cloud with particles of dust forming a disk in motion and at the expense of its mass, in the center of which a new star was born, which we all know as the Sun.
So what celestial bodies are called planets,members of the solar system? The answer to this question is very simple: all objects that have their own orbit and which rotate around a common, central star and are called planets of the solar system. They are divided into two small groups, four objects in each:
• Earth group of planets - Mars, Venus, Earth and Mercury. All of them have a stony surface and a small size, being at a closer distance to the Sun than others.
• Planet giants - Neptune, Saturn, Jupiter and Uranus. Large, consisting mainly of gas of the planet, with rings characteristic for them only, which are formed from a multitude of rocky debris and ice dust.
Until August 25, 2006 it was believed that inthe composition of the solar system is nine planets. But after clarifying the definitions by which it was accepted what it is possible to call a planet in the scientific world, Pluto, which previously entered the Solar System as the ninth, most remote object, moved into the category of dwarf ones.
What was the reason for the adoption of thissolutions? The point is that with the improvement of telescopes and other astronomical equipment, scientists have discovered similar in characteristics with Pluto, heavenly objects, the number of which will eventually increase. In order to exclude possible confusion in the future and more precise requirements were introduced to which celestial bodies are called planets.
Conclusion
The study of planets and stars will continuea very long time, and no one can know how many more riddles conceal in themselves the cosmic distances. So for many years the question of how the life on our planet, in the solar system and in the whole universe was born, will remain for many years.
