Description of the belt of asteroids of the solar system. Asteroids of the main belt

The description of the solar system contains not only information about the eight planets and Pluto, but also several other structures, including a large number of cosmic bodies. These include the Kuiper belt, the scattered disk, the Oort cloud, and the asteroid belt. The latter will be discussed below.

Definition

The term "asteroid" was borrowed by William Herschel from the composer Charles Burnie. The word has a Greek origin and means "like a star." The use of this term was due to the fact that when studying the space through the telescope, the asteroids seemed like stars: they looked like dots unlike planets, which resembled discs.

As such, there is no definition of the term today. The main characteristic feature of the objects of the belt of asteroids and similar structures is the size. The lower limit is 50 m in diameter. The smaller cosmic bodies are already meteors. The upper boundary is the diameter of the dwarf planet Ceres, almost 1000 km.

Location and some features

The asteroid belt is located between the orbits of Mars and Jupiter. Today, more than 600,000 of its objects are known, of which over 400,000 have their own number or even a name. Approximately 98% of the latter - objects of the asteroid belt, remote from the Sun at a distance of 2.2 to 3.6 astronomical units. The largest body among them is Ceres. At the meeting of the IAU in 2006, it, together with Pluto and several other objects, received the status of a dwarf planet. The following in size, Vesta, Pallada and Gigeya together with Ceres make up 51% of the total mass of the asteroid belt.

The form

The cosmic bodies that make up the belt, besides the dimensions, also have a number of basic characteristics. All of them are stony objects, orbiting around their Sun. Observations of asteroids made it possible to establish that, as a rule, they have an irregular shape and rotate. Pictures taken by spaceships flying through the asteroid belt in the solar system have confirmed these assumptions. According to scientists, this form is the result of frequent collisions of asteroids with each other and other objects.

Composition

To date, astronomers have identified three classes of asteroids according to the basic substance that forms part of them:

• Carbon (class C);
• Silicate (class S) with a predominance of silicon;
• Metal (class M).

The first account for about 75% of all known asteroids. This classification, however, is not considered acceptable by some scientists. In their opinion, the existing data do not allow us to unequivocally state which element prevails in the composition of the cosmic bodies of the asteroid belt.

In 2010, a group of astronomers made an interesting discovery concerning the composition of asteroids. Scientists found on the surface of Themis, a fairly large object of this zone, water ice. The find confirms indirectly the hypothesis that one of the sources of water on the young Earth was asteroids.

Other characteristics

The average speed with which the objects of this region fly around the Sun is 20 km / s. At the same time for one revolution, asteroids of the main belt spend from three to nine Earth years. For most of them, a small inclination of the orbit to the plane of the ecliptic is characteristic - 5-10 °. However, there are also objects, the flight trajectory of which makes with the plane of rotation of the Earth around the luminary a more impressive angle, up to 70 °. This characteristic formed the basis for the classification of asteroids into two subsystems: flat and spherical. The inclination of the orbits of objects of the first type is less than or equal to 8º, the second - more than the specified value.

Occurrence

In the century before last, the hypothesis of the deceased Phaethon was widely discussed in scientific circles. The distance from Mars to Jupiter is quite impressive, and here could pass the orbit of another planet. However, such views are now considered obsolete. Modern astronomers adhere to the version that on the site where the asteroid belt passes , the planet simply could not arise. The reason for this is in Jupiter. The gas giant, even at the early stages of its formation, had a gravitational effect on the region lying closer to the Sun. He attracted part of the substance from this zone to himself. Not captured by Jupiter bodies were scattered in different directions, the speed of proto-asteroid increased, the number of collisions increased. As a result, they not only did not increase the mass and volume, but even became smaller. In the process of such transformations, the probability of the appearance of a planet between Jupiter and Mars became zero.

Constant influence

Jupiter still does not leave the asteroid belt alone. Its powerful gravitation causes the orbits of some bodies to change. Under its influence, the so-called forbidden zones appeared, in which there are practically no asteroids. The body that flies here due to a collision with another object is pushed out of the zone. Sometimes the orbit changes so much that it leaves the asteroid belt.

Additional rings

The main belt of asteroids is not alone. On its external border are located two less impressive similar formations. One of these rings is located directly in the orbit of Jupiter and is represented by two groups of objects:

• "Greeks" outpace the gas giant by about 60º;
• "Trojans" are lagging behind by the same number of degrees.

A characteristic feature of these bodies is the stability of their motion. It is possible due to the location of asteroids at the "Lagrange points", where all the gravitational effects on these objects are balanced.

Despite the relatively close location to the Earth, the asteroid belt has not been studied enough and keeps many secrets. The first of these, of course, is the origin of the small bodies of the solar system. Existing assumptions on this score, although sounding convincingly enough, have not yet been unambiguously confirmed.

Some aspects of the structure of asteroids also raise questions. It is known, for example, that even related objects of the belt differ in some respects from each other in some respects. The study of the characteristics of asteroids and their origin is necessary both for understanding the events preceding the formation of the solar system in the form known to us, and for constructing theories about processes occurring in remote parts of space in the systems of other stars.