The central star of our system, in different orbits around which all the planets pass, is called the Sun. Its age is about 5 billion years. This is a yellow dwarf, so the size of the star is small. Its thermonuclear reactions are consumed not very quickly. The solar system has reached approximately the middle of its life cycle. After 5 billion years, the balance of gravitational forces will be disturbed, the star will increase in size, gradually heat up. Fusion converts all of the Sun's hydrogen into helium. By this time, the size of the star will be three times larger. Ultimately, the star will cool down, decrease. Today the Sun is made up almost entirely of hydrogen (90%) and some helium (10%).
Today, the satellites of the Sun are 8 planets around which other celestial bodies, several dozen comets, as well as a huge number of asteroids revolve. All these objects move in their orbit. If you add up the mass of all the satellites of the Sun, it turns out that they are 1000 times lighter than their star. The main celestial bodies of the system deserve detailed consideration.
General concept of the solar system
To consider the satellites of the Sun, it is necessaryget acquainted with the definitions: what is a star, planet, satellite, etc. A star is a body that radiates light and energy into space. This is possible due to the thermonuclear reactions occurring in it and the processes of compression under the influence of gravity. There is only one star in our system, the Sun. 8 planets revolve around it.
A planet today is a celestial body that revolves around a star and has a spherical (or close to it) shape. Such objects do not emit light (they are not stars). They can reflect it. Also, the planet does not have other large celestial bodies near its orbit.
A satellite is also called an object that revolves around other, larger stars or planets. It is kept in orbit by the force of gravity of this large celestial body. To understand how many satellites the Sun has, it should be noted that this list, in addition to planets, includes asteroids, comets, and meteorites. It is almost impossible to count them.
Planets
Until recently, it was believed that our system has 9 planets. After much discussion, Pluto was removed from this list. But it is also part of our system.
8 major planets are kept in their orbits by the Sun. A satellite (planet) can also have celestial bodies revolving around it. There are quite large objects. All planets are divided into 2 groups. The first includes the inner satellites of the Sun, and the second - the outer ones.
The planets of the terrestrial (first) group are as follows:
- Mercury (closest to the star).
- Venus (the hottest planet).
- Earth.
- Mars (the most accessible object for exploration).
They are composed of metals, silicates, their surface is hard. The outer group are the gas giants. These include:
- Jupiter.
- Saturn.
- Uranium.
- Neptune.
Their composition is characterized by a high content of hydrogen and helium. These are the largest planets in the system.
Satellites of planets
Considering the question of how many satellites the Sun has, we should mention the celestial bodies revolving around the planets. In ancient Greece, Venus, Mercury, Sun, Mars, Moon, Jupiter, Saturn were considered planets. Only in the 16th century the Earth was included in this list. The sun has taken in the understanding of people its central importance in our system. The moon turned out to be a satellite of the Earth.
With the advent of more advanced technology, it has been found that almost all planets have moons. Only Venus and Mercury do not have them. Today, about 60 satellites of the planets are known, which are characterized by different sizes. The least known of them is Leda. This moon of Jupiter is only 10 km in diameter.
Most of these objects, located in the orbit of gas giants, were discovered using automatic space technology. She provided scientists with photographs of such celestial objects.
Mercury and Venus
Two rather small objects are closest to our star. The Sun's satellite Mercury is the smallest planet in the system. Venus is slightly larger than him. But both of these planets do not have their moons.
Mercury has a highly rarefied helium atmosphere. It orbits its star in 88 Earth days. But the duration of a revolution around its axis for this planet is 58 days (by our standards). The temperature on the sunny side reaches +400 degrees. At night, cooling down to -200 degrees is recorded here.
Venus has an atmosphere composed of hydrogen with admixtures of nitrogen and oxygen. There is a greenhouse effect here. Therefore, the surface heats up to a record +480 degrees. This is more than on Mercury. This planet is best seen from Earth as its orbit is closest to us.
Earth
Our planet is the largest among all representatives of the terrestrial group. It is unique in many ways. Earth has the largest celestial body in its orbit among the first 4 planets from a star. This is the moon. The satellite of the Sun, which is our planet, differs significantly from all in its atmosphere. Thanks to this, life became possible on it.
About 71% of the surface is water. The remaining 29% is land. The basis of the atmosphere is nitrogen. It also includes oxygen, carbon dioxide, argon and water vapor.
Earth's moon moon has no atmosphere. There is no wind, sounds, weather on it. It is a rocky, bare surface covered with craters. On Earth, traces of meteor impacts are smoothed out under the influence of the vital activity of various species,thanks to wind and weather. There is nothing on the moon. Therefore, all traces of her past are reflected very clearly.
Mars
This is the closing planet of the terrestrial group. It is called the "Red Planet" due to the high content of iron oxide in the soil. It is quite similar to the Earth satellite. It revolves around the Sun for 678 Earth days. Scientists believed that life could once exist here. However, studies have not confirmed this. Mars' moons are Phobos and Deimos. They are smaller than the Moon.
It's colder here than on our planet. At the equator, the temperature reaches 0 degrees. At the poles, it drops to -150 degrees. This world is already available for astronaut flights. The spacecraft can reach the planet in 4 years.
In ancient times, rivers flowed on the surface of the planet. There was water here. Now there are ice caps at the poles. Only they do not consist of water, but of atmospheric carbon dioxide. Scientists suggest that water may be frozen in large chunks below the surface of the planet.
Gas giants
Behind Mars are the largest objects that accompany the Sun. The planets (satellites of the planets of this group) were studied using various techniques. The largest object in our system is Jupiter. It is 2.5 times more massive than all the planets orbiting the Sun combined. It consists of helium, hydrogen (which is similar to our star). The planet radiates heat. However, to be considered a star, Jupiter needs to become 80 times heavier. Has 63 satellites.
Saturnslightly smaller than Jupiter. He is known for his rings. These are ice particles of various diameters. The density of the planet is less than that of water. Has 62 satellites.
Uranus and Neptune are even further away than the previous two planets. They were discovered with a telescope. They contain a large number of high-temperature modifications of ice. These are Ice Giants. Uranus has 23 moons and Neptune has 13.
Pluto
The satellites of the sun are also complemented by a small object called Pluto. From 1930 to 2006, he held the title of the planet. However, after lengthy discussions, scientists came to the conclusion that this is not a planet. Pluto falls into a different category. From the point of view of the current planetary classification, this is the prototype of dwarf planets. The surface of the object is covered with frozen ice made of methane and nitrogen. Pluto has 1 satellite.
Having studied the main satellites of the Sun, it should be said that this is a whole system consisting of a large number of different objects. Their characteristics and indicators are different. What unites all these objects is a force that makes them constantly rotate around their central star.
