Space has long attracted people's attention. Astronomers began to study the planets of the solar system in the Middle Ages, looking at them through primitive telescopes. But a thorough classification, description of the features of the structure and movement of celestial bodies became possible only in the 20th century. With the advent of powerful equipment, state-of-the-art observatories and spacecraft, several previously unknown objects have been discovered. Now each student can list all the planets of the solar system in order. Almost all of them have been landed by a space probe, and so far man has only been on the Moon.
What is the solar system
The universe is huge and includes many galaxies. Our solar system is part of the Milky Way galaxy, which has over 100 billion stars. But there are very few that look like the Sun. Basically, they are all red dwarfs, which are smaller in size and do not shine as brightly. Scientists have suggested that the solar system was formed after the emergence of the sun. Its huge field of attraction captured a gas-dust cloud, from which, as a result of gradual cooling, particles were formed.solid. Over time, celestial bodies formed from them. It is believed that the Sun is now in the middle of its life path, so it will exist, as well as all celestial bodies dependent on it, for several billion more years. Near space has been studied by astronomers for a long time, and any person knows what planets of the solar system exist. Photos of them, taken from space satellites, can be found on the pages of various information resources dedicated to this topic. All celestial bodies are held by the Sun's strong gravitational field, which makes up over 99% of the solar system's volume. Large celestial bodies revolve around the star and around their axis in one direction and in one plane, which is called the plane of the ecliptic.
Planets of the solar system in order
In modern astronomy, it is customary to consider celestial bodies starting from the Sun. In the 20th century, a classification was created, which includes 9 planets of the solar system. But recent space exploration and the latest discoveries have prompted scientists to revise many positions in astronomy. And in 2006, at the international congress, due to its small size (a dwarf, not exceeding three thousand km in diameter), Pluto was excluded from the number of classical planets, and eight of them remained. Now the structure of our solar system has taken on a symmetrical, slender appearance. It includes four terrestrial planets: Mercury, Venus, Earth and Mars, then comes the asteroid belt, followed by four giant planets: Jupiter, Saturn, Uranus andNeptune. On the outskirts of the solar system, there is also an asteroid belt, which scientists have called the Kuiper belt. This is where 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 size;
- hard surface, high density and similar composition (oxygen, silicon, aluminum, iron, magnesium and other heavy elements);
- presence of atmosphere;
- the same structure: a core of iron with nickel impurities, a mantle consisting of silicates, and a crust of silicate rocks (except for Mercury - it has no crust);
- a small number of satellites - only 3 for four planets;
- fairly weak magnetic field.
Features of the giant planets
As for the outer planets, or gas giants, they have the following similar characteristics:
- large sizes and masses;
- they do not have a solid surface and are composed of gases, mainly helium and hydrogen (which is why they are also called gas giants);
- liquid core consisting of metallic hydrogen;
- high rotation speed;
- strong magnetic field, which explains the unusual nature of many processes occurring on them;
- there are 98 satellites in this group, most of which belong to Jupiter;
- mosta characteristic feature of gas giants is the presence of rings. All four planets have them, although they are not always noticeable.
The first planet is 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 fluctuations: from -180 to +430 degrees. Mercury is moving very fast in its orbit. Maybe that's why he got such a name, because in Greek mythology Mercury is the messenger of the gods. There is almost no atmosphere here, and the sky is always black, but the Sun shines very brightly. However, there are places at the poles where its rays never hit. This phenomenon can be explained by the tilt of the axis of rotation. No water was found on the surface. This circumstance, as well as the anomalously high daytime temperature (as well as the low nighttime temperature) fully explain the fact that there is no life on the planet.
Venus
If you study the planets of the solar system in order, then the second one is Venus. People could observe her in the sky in ancient times, but since she was shown only in the morning and in the evening, it was believed that these were 2 different objects. By the way, our Slavic ancestors called her Flicker. It 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, makingcomplete revolution in 243.02 Earth days. Of course, the conditions on Venus are very different from those on Earth. It is twice as close to the Sun, so it is very hot there. The high temperature is also explained by the fact that thick clouds of sulfuric acid and an 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 also the fact that it rotates in the opposite direction, compared to most planets. Nothing more is known about this celestial object yet.
Third planet from the Sun
The only place in the solar system, and indeed in the entire universe known to astronomers, where life exists, is the planet Earth. In the terrestrial group, it has the largest dimensions. What are her other distinguishing features?
- The biggest gravity among the terrestrial planets.
- Very strong magnetic field.
- High density.
- She is the only one among all the planets that has a hydrosphere, which contributed to the formation of life.
- It has the largest satellite compared to its size, which stabilizes its tilt relative to the Sun and affects natural processes.
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 -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 drops are observed. The planet Mars is 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. After all, in the past there was water on the surface of the planet. Such a conclusion can be drawn from the fact that there are large ice caps at the poles, and the surface is covered with many furrows, which could be dried up river beds. In addition, there are some minerals on Mars that can only be formed in the presence of water. Another feature of the fourth planet is the presence of two satellites. Their unusualness is that Phobos gradually slows down its rotation and approaches the planet, while Deimos, on the contrary, moves away.
What Jupiter is famous for
The fifth planet is the largest. 1300 Earths would fit in the volume of Jupiter, and its mass is 317 times more than the earth. Like all gas giants, its structure is hydrogen-helium, reminiscent of the composition of stars. Jupiter is the most interesting planet that has many unique features:
- this is the third brightest celestial body after the Moon and Venus;
- Jupiter has the strongest magnetic field of any planet;
- it completes a full rotation around its axis in just 10 Earth hours - faster than other planets;
- an interesting feature of Jupiter is a large red spot - as seen from Earthatmospheric vortex rotating counterclockwise;
- like all giant planets, it has rings, though not as bright as those of Saturn;
- this planet has the largest number of satellites. He has 63 of them. The most famous are Europa, where water was found, Ganymede - 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
This 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 have been found on its surface. Scientists have found that Saturn is the most rarefied planet. Its density is less than that of water. This gas giant rotates very quickly - it completes one revolution in 10 Earth hours, as a result of which the planet is flattened from the sides. Huge speeds on Saturn and near the wind - up to 2000 kilometers per hour. It's more than the speed of sound. Saturn has another distinctive feature - it keeps 60 satellites in its field of 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, exploring 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 itherself. The four rings of Saturn are 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 while lying on its side. The change of seasons on the planet is also unusual: winter reigns there for 42 Earth years, and the Sun does not appear at all, summer also lasts 42 years, and the Sun does not set at this time. In spring and autumn, the luminary appears every 9 hours. Like all giant planets, Uranus has rings and many satellites. As many as 13 rings revolve around it, but they are not as bright as those of Saturn, and the planet holds only 27 satellites. If we compare Uranus with the Earth, then it is 4 times larger than it, 14 times heavier and is located at a distance from the Sun, in 19 times the path to the sun from our planet.
Neptune: the invisible planet
After Pluto was excluded from the number of planets, Neptune became the last from the Sun in the system. It is located 30 times farther from the star than the Earth, and is not visible from our planet even through a telescope. Scientists discovered it, so to speak, by chance: observing the features of the movementthe planets closest to it and their satellites, they concluded that there must be another large celestial body beyond the orbit of Uranus. 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 appears 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 bigger than Earth and 17 times heavier, but the force of gravity is almost the same as on our planet;
- the largest of the 13 moons of this giant is Triton. It is always turned to the planet on one side and slowly approaches it. Based on these signs, scientists have suggested that it was captured by Neptune's gravity.
There are about a hundred billion planets in the entire Milky Way galaxy. So far, scientists cannot 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 has faded a little, but even children know the name of the planets in the solar system.
