Since ancient times, space has attracted people's attention. Astronomers began to study the planets of the solar system back in the Middle Ages, examining them with primitive telescopes. But a thorough classification, description of the structural features and movement of celestial bodies became possible only in the 20th century. With the advent of powerful equipment, equipped with the latest technology of observatories and spacecraft, several previously unknown objects were discovered. Now each student can list all the planets of the solar system in order. A space probe descended on almost all of them, and so far man has only visited the moon.
What is a solar system?
The universe is huge and includes many galaxies. Our solar system is part of the Milky Way galaxy, in which more than 100 billion stars. But there are very few that look like the sun. Basically, all of them are red dwarfs, which are smaller in size and shine less brightly. Scientists have suggested that the solar system formed after the emergence of the sun. A gas-dust cloud captured its huge field of attraction, from which particles of solid matter formed as a result of gradual cooling. Over time, celestial bodies formed from them. It is believed that the Sun is now in the middle of its life path, therefore, it will exist, as well as all celestial bodies dependent on it, for several billion years. Near space astronomers have long studied, and anyone knows what planets of the solar system exist. Their photos taken from space satellites can be found on the pages of various information resources on this topic. All celestial bodies are held by a strong field of gravity of the Sun, which is more than 99% of the volume of the solar system. Large celestial bodies rotate around the star and around its axis in the same direction and in the same plane, which is called the plane of the ecliptic.
Planets of the solar system in order
In modern astronomy, celestial bodies, starting from the Sun, are considered to be. In the 20th century, a classification was created, which includes 9 planets of the solar system. But recent space exploration and recent discoveries have prompted scientists to revise many of the provisions in astronomy. And in 2006, at the international congress, because of its small size (a dwarf with a diameter not exceeding three thousand kilometers), Pluto was excluded from the number of classical planets, and there were eight of them. Now the structure of our solar system has assumed a symmetrical, harmonious appearance. It includes four terrestrial planets: Mercury, Venus, Earth and Mars, then comes the asteroid belt, followed by four giant planets: Jupiter, Saturn, Uranus and Neptune. On the outskirts of the solar system also passes the asteroid belt, which scientists called the Kuiper belt. It is in it that Pluto is located. These places are still little studied due to their remoteness from the Sun.
Features of the terrestrial planets
What makes it possible to attribute these celestial bodies to one group? We list the main characteristics of the inner planets:
- relatively small sizes;
- hard surface, high density and similar composition (oxygen, silicon, aluminum, iron, magnesium and other heavy elements);
- the presence of the atmosphere;
- the same structure: a core of iron with impurities of nickel, a mantle consisting of silicates, and a crust of silicate rocks (except Mercury - it does not have a crust);
- a small number of satellites - only 3 on four planets;
- rather weak magnetic field.
Features of giant planets
As for the outer planets, or gas giants, they have such similar characteristics:
- large sizes and masses;
- they do not have a solid surface and consist of gases, mainly helium and hydrogen (therefore they are also called gas giants);
- a liquid core consisting of metallic hydrogen;
- high rotation speed;
- a strong magnetic field, which explains the unusual nature of many processes taking place on them;
- there are 98 satellites in this group, most of which belong to Jupiter;
- The most characteristic feature of gas giants is the presence of rings. All four planets have them, however, they are not always noticeable.
First Planet - Mercury
It is located closest to the Sun. Therefore, from its surface, the luminary looks three times larger than from the Earth. This also explains the strong temperature drops: from -180 to +430 degrees. Mercury moves very fast in orbit. Maybe that's why he got that name, because in Greek mythology, Mercury is the messenger of the gods. There is practically no atmosphere, and the sky is always black, but the sun shines very brightly. However, at the poles there are places where its rays never fall. This phenomenon can be explained by the inclination of the axis of rotation. No water was found on the surface. This circumstance, as well as the abnormally high daytime temperature (as well as the low night temperature) completely explain the fact of the absence of life on the planet.
Venus
If you study the planets of the solar system in order, then the second in a row is Venus. Her people could be seen in the sky in antiquity, but since it was shown only in the morning and in the evening, it was believed that these were 2 different objects. By the way, our ancestors-Slavs called it Merzana. This is the third brightest object in our solar system. Previously, people called it the morning and evening star, because it is best seen before sunrise and sunset. Venus and Earth are very similar in structure, composition, size and gravity. Around its axis, this planet moves very slowly, making a complete revolution in 243.02 Earth days. Of course, the conditions on Venus are very different from earthly ones. It is two times closer to the Sun, so it is very hot there. The high temperature is also explained by the fact that the dense clouds of sulfuric acid and the atmosphere of carbon dioxide create a greenhouse effect on the planet. In addition, the pressure at the surface is 95 times greater than on Earth. Therefore, the first ship that visited Venus in the 70s of the 20th century survived there for no more than an hour. A feature of the planet is that it rotates in the opposite direction, compared with most planets. Nothing more is known to astronomers about this celestial object.
Third planet from the Sun
The only place in the solar system, and in the entire universe known to astronomers, where life exists, is planet Earth. In the earth group, it has the largest sizes. What are its distinguishing features?
- The largest gravity among the planets of the earth group.
- Very strong magnetic field.
- High density.
- She is the only one among all the planets to have a hydrosphere, which contributed to the formation of life.
- It has the largest, in comparison with its size, satellite, which stabilizes its tilt relative to the Sun and affects natural processes.
The planet Mars
This is one of the smallest planets in our galaxy. If we consider the planets of the solar system in order, then Mars is the fourth from the Sun. Its atmosphere is very rarefied, and the pressure on the surface is almost 200 times less than on Earth. For the same reason, very strong temperature differences are observed. The planet Mars has been little studied, although it has long attracted the attention of people. According to scientists, this is the only celestial body on which life could exist. Indeed, in the past there was water on the surface of the planet. This conclusion can be made on the basis that there are large ice caps at the poles, and the surface is covered with many furrows, which could be dried river beds. In addition, there are some minerals on Mars, the formation of which is possible only in the presence of water. Another feature of the fourth planet is the presence of two satellites. Their unusualness is that Phobos is gradually slowing down its rotation and approaching the planet, and Deimos, on the contrary, is moving away.
What is famous for Jupiter
The fifth planet is the largest. The volume of Jupiter would fit 1300 Earths, and its mass is 317 times greater than the Earth. Like all gas giants, its structure is hydrogen-helium, resembling the composition of stars. Jupiter is the most interesting planet, which has many characteristic features:
- it is the third brightest celestial body after the Moon and Venus;
- on Jupiter, the strongest magnetic field among all the planets;
- he completes a complete revolution around the axis in just 10 earth hours - faster than other planets;
- An interesting feature of Jupiter is a large red spot - this is how the atmospheric vortex, rotating counterclockwise, is visible from Earth;
- like all giant planets, it has rings, though not as bright as that of Saturn;
- this planet has the largest large number of satellites. He has 63 of them. The most famous is Europe, where they found water, Ganymede is the largest satellite of the planet Jupiter, as well as Io and Calisto;
- Another feature of the planet is that in the shade the surface temperature is higher than in places illuminated by the Sun.
Planet saturn
It is the second largest gas giant, also named after the ancient god. It consists of hydrogen and helium, but traces of methane, ammonia and water were found on its surface. Scientists have found that Saturn is the most sparse planet. Its density is less than that of water. This gas giant rotates very quickly - it makes one revolution in 10 Earth hours, as a result of which the planet is flattened from the sides. Huge speeds on Saturn and the wind - up to 2000 kilometers per hour. This is more than the speed of sound. Saturn has another distinctive feature - it holds 60 satellites in the field of its attraction. The largest of them - Titan - is the second largest in the entire solar system. The uniqueness of this object lies in the fact that, by examining its surface, scientists first discovered a celestial body with conditions similar to those that existed on Earth about 4 billion years ago. But the most important feature of Saturn is the presence of bright rings. They encircle the planet around the equator and reflect more light than itself. The four rings of Saturn is the most amazing phenomenon in the solar system. Unusually, the inner rings move faster than the outer ones.
Ice Giant - Uranus
So, we continue to consider the planets of the solar system in order. The seventh planet from the Sun is Uranus. It is the coldest of all - the temperature drops to -224 ° C. In addition, scientists did not find metallic hydrogen in its composition, but found modified ice. Because Uranus is classified as a separate category of ice giants. An amazing feature of this celestial body is that it rotates lying on its side. The change of seasons on the planet is also unusual: for 42 earth years, winter reigns there, and the Sun does not appear at all, summer also lasts 42 years, and the Sun does not set at this time. In the spring and autumn, the luminary appears every 9 hours. Like all giant planets, Uranus has rings and many satellites. As many as 13 rings rotate around it, but they are not as bright as Saturn’s, and the planet holds only 27 satellites. If we compare Uranus with the Earth, it is 4 times larger than it, 14 times heavier and located at a distance from the Sun, 19 times the path to the luminary from our planet.
Neptune: The Invisible Planet
After Pluto was excluded from the number of planets, Neptune became the last of the Sun in the system. It is located 30 times further from the star than the Earth, and from our planet is not even visible through a telescope. Scientists discovered it, so to speak, by accident: observing the peculiarities of the motion of the planets closest to it and their satellites, they concluded that beyond the orbit of Uranus there should be another large celestial body. After discovery and research, interesting features of this planet were revealed:
- due to the presence of a large amount of methane in the atmosphere, the color of the planet from space seems blue-green;
- Neptune’s orbit is almost perfectly round;
- the planet rotates very slowly - it completes one circle in 165 years;
- Neptune is 4 times larger than Earth and 17 times heavier, but the force of attraction is almost the same as on our planet;
- the largest of this giant's 13 moons is Triton. He is always turned to the planet on one side and slowly approaches it. According to these signs, scientists suggested that he was captured by the attraction of Neptune.
In the entire galaxy, the Milky Way - about one hundred billion planets. While scientists can not even study some of them. But the number of planets in the solar system is known to almost all people on Earth. True, in the 21st century, interest in astronomy faded a little, but even children know the name of the planets of the solar system.