The solar system is a tiny structure across the universe. At the same time, its dimensions for man are truly grandiose: each of us, living on the fifth largest planet, can hardly even evaluate the scale of the Earth. The modest dimensions of our house, perhaps, are felt only when you look at it from the porthole of a spaceship. A similar feeling arises when viewing images of the Hubble telescope: the universe is huge and the solar system occupies only a small portion of it. However, we can study and investigate it, using the data obtained to interpret the phenomena of deep space.
Universe coordinates
Scientists determine the location of the solar system by indirect signs, since we cannot observe the structure of the galaxy from the side. Our piece of the universe is located in one of the spiral arms of the Milky Way. The Orion arm, so named because it passes near the constellation of the same name, is considered an offshoot of one of the main galactic arms. The sun is located closer to the edge of the disk than to its center: the distance to the latter is approximately 26 thousand light years.
Scientists suggest that the location of our piece of the universe has one advantage over others. On the whole, the Galaxy of the Solar System, the Milky Way, has stars that, due to the peculiarities of their movement and interaction with other objects, either plunge into spiral arms or emerge from them. However, there is a small area called the corotation circle, where the speed of stars and spiral arms coincides. Space bodies located here are not exposed to the turbulent processes characteristic of the arms. The sun with planets also belongs to the corotation circle. This situation is considered one of the conditions that contributed to the emergence of life on Earth.
Solar system diagram
The central body of any planetary community is a star. The name of the solar system gives an exhaustive answer to the question, around which luminary the earth and its neighbors are moving. The sun is a third-generation star in the middle of its life cycle. It has been shining for more than 4.5 billion years. About the same number of planets revolve around him.
The scheme of the solar system today includes eight planets: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Uranus, Neptune (about where Pluto went, a little lower). They are conditionally divided into two groups: terrestrial planets and gas giants.
"Relatives"
The first type of planets, as the name implies, includes the Earth. In addition to her belong to him Mercury, Venus and Mars.
All of them have a set of similar characteristics. The terrestrial planets are mainly composed of silicates and metals. They are distinguished by high density. All of them have a similar structure: the iron core with an admixture of nickel is wrapped in a silicate mantle, the upper layer is a crust, including silicon compounds and incompatible elements. A similar structure is violated only in Mercury. The smallest and
closest planet to the Sun does not have a crust: it is destroyed by meteorite bombing.
The largest planet of the group is Earth, followed by Venus, then Mars. There is a certain order of the solar system: the planets of the earth group make up its inner part and are separated from the gas giants by an asteroid belt.
Major planets
Gas giants include Jupiter, Saturn, Uranus and Neptune. All of them are much larger than the objects of the earth group. Giants have a lower density and, unlike the planets of the previous group, are composed of hydrogen, helium, ammonia and methane. Giant planets do not have such a surface, it is considered the conditional boundary of the lower atmosphere. All four objects rotate very quickly around their axis, possess rings and satellites. The most impressive planet in size is Jupiter. It is accompanied by the largest number of satellites. Moreover, Saturn has the most impressive rings.
The characteristics of the gas giants are interconnected. If they were approaching the Earth in size, they would have a different composition. Only a planet with a sufficiently large mass can hold light hydrogen.
Dwarf planets
It’s time to study what the solar system represents — grade 6. When today's adults were at this age, the cosmic picture looked a little different for them. The solar system at that time included nine planets. Pluto was listed last. This was until 2006, when the meeting of the IAU (International Astronomical Union) adopted the definition of the planet and Pluto ceased to correspond to it. One of the points is: “The planet dominates its orbit.” Pluto's trajectory is littered with other objects that exceed the total mass of the former ninth planet. For Pluto and several other objects, the concept of “dwarf planet” was introduced.
After 2006, all bodies in the solar system were thus divided into three groups:
planets - objects are large enough, able to clear their orbit;
small bodies of the solar system (asteroids) - objects that are so small that they cannot achieve hydrostatic equilibrium, that is, take a rounded or close shape to it;
dwarf planets occupying an intermediate position between the two previous types: they reached hydrostatic equilibrium, but did not clear the orbit.
The last category today officially includes five bodies: Pluto, Eris, Makemake, Haumea and Ceres. The latter refers to the asteroid belt. Makemake, Haumea and Pluto belong to the Kuiper belt, and Eris - to the scattered disk.
Asteroid belt
The peculiar border that separates the planets of the earth's group from the gas giants is exposed to Jupiter throughout its existence. Due to the presence of a huge planet, the asteroid belt has a number of features. So, his images give the impression that this is a very dangerous zone for spacecraft: the ship can be damaged by an asteroid. However, this is not entirely true: the influence of Jupiter has led to the fact that the belt is a rather rarefied cluster of asteroids. Moreover, the bodies that make up it are quite modest in size. During the formation of the belt, Jupiter's gravity influenced the orbits of large cosmic bodies that accumulated here. As a result, collisions constantly occurred, leading to the appearance of small fragments. A significant part of these fragments, under the influence of the same Jupiter, was expelled outside the solar system.
The total mass of the bodies that make up the Asteroid belt is only 4% of the mass of the moon. They consist mainly of rocks and metals. The largest body in this area is the dwarf planet Ceres, followed by the asteroids Pallas, Vest and Hygea.
Kuiper Belt
The scheme of the solar system also includes another area populated by asteroids. This is the Kuiper belt, located beyond the orbit of Neptune. The objects located here, including Pluto, were called trans-Neptunian. Unlike the asteroids of the belt, which lies between the orbits of Mars and Jupiter, they consist of ice - water, ammonia and methane. The Kuiper belt is 20 times wider than the asteroid and much more massive.
Pluto in its structure is a typical object of the Kuiper belt. He is the largest body of the region. Two more dwarf planets are also located here: Makemake and Haumea.
Scattered disk
The dimensions of the solar system are not limited to the Kuiper belt. Behind it is the so-called scattered disk and the hypothetical Oort cloud. The first partially intersects with the Kuiper belt, but lies much farther than it in space. This is the place where the short-period comets of the Solar System originate. They are characterized by an orbital period of less than 200 years.
The objects of a scattered disk, including comets, as well as bodies from the Kuiper belt, consist mainly of ice.
Oort Cloud
The space where the long-period comets of the solar system originate (with a period of thousands of years) is called the Oort cloud. To date, there is no direct evidence of its existence. Nevertheless, many facts have been discovered that indirectly confirm the hypothesis.
Astronomers suggest that the outer boundaries of the Oort cloud are distant from the Sun at a distance of 50 to 100 thousand astronomical units. In size, it is a thousand times larger than the Kuiper belt and the scattered disk combined. The outer boundary of the Oort cloud is also considered the boundary of the solar system. The objects located here are exposed to nearby stars. As a result of this, comets are formed whose orbits pass through the central parts of the solar system.
Unique structure
Today, the solar system is the only part of the cosmos known to us where there is life. Last but not least, the possibility of its occurrence was influenced by the structure of the planetary system and its placement in the corotation circle. The land, located in the "zone of life", where sunlight does not become so destructive, could be as dead as its closest neighbors. Comets appearing in the Kuiper belt, the scattered disk and the Oort cloud, as well as large asteroids could destroy not only dinosaurs, but even the very probability of the occurrence of living matter. A huge Jupiter protects us from them, attracting similar objects to itself or changing their orbit.
While studying the structure of the solar system, it is difficult not to fall under the influence of anthropocentrism: it seems as if the Universe did everything just so that people could appear. This is probably not entirely true, but a huge number of conditions, the slightest violation of which would lead to the death of all living things, persistently incline to such thoughts.