Description solar system not only contains information about the eight planets and Pluto, but several structures, including a large number of celestial bodies.These include the Kuiper belt, the scattered disc, the Oort cloud, and the asteroid belt.The latter will be discussed below.
Determination
term "asteroid" was adapted by William Herschel composer Charles Burney.The word is of Greek origin and means "like a star".The use of this term was due to the fact that the study of the cosmos through the telescope asteroids seemed like stars: looked like a point unlike planets that resembled wheels.
As such, there is no definition of the term today.The main characteristic feature of the objects of the asteroid belt, and similar structures - size.The lower limit - a diameter of 50 m. Space smaller body - this is a meteor.The upper limit - the diameter of the dwarf planet Ceres, nearly 1000 km.
Location and some features
asteroid belt located between the orbits of Mars and Jupiter.Today there are more than 600,000 of its facilities, of which over 400,000 have their own room, or even the name.Approximately 98% of the latter - the objects of the asteroid belt, far from the Sun at a distance of 2.2 to 3.6 astronomical units.The largest body among them - Ceres.At a meeting of the MAC in 2006, she, along with Pluto and several other objects acquired the status of dwarf planet.The following size Vesta, Pallas and Ceres gig with 51% of the total mass of the asteroid belt.
form
cosmic bodies that make up the belt, in addition to the dimensions are still a number of key characteristics.All of them are rocky objects circulating in their orbits around the sun.Observations asteroids possible to establish that, generally, they are irregularly shaped and are rotating.Pictures taken spaceships flying through the asteroid belt in our solar system, we have confirmed these assumptions.According to the researchers, this form - the result of frequent collisions with each other asteroids and other objects.
composition
Today, astronomers are three classes according to the asteroid main substances in their composition:
- carbon (Class C);
- silicate (Class S) and the predominance of silicon;
- metal (Class M).
first account for about 75% of all known asteroids.This classification, however, some scholars are not considered acceptable.In their view, the existing data did not conclusively say which element dominates in the composition of cosmic bodies of the asteroid belt.
In 2010, a group of astronomers has made an interesting discovery concerning the composition of asteroids.Scientists have found on the surface of Themis, a sufficiently large area of the object, water ice.The find confirms indirectly the hypothesis that one of the sources of water on the young Earth asteroids were.
Other features
average rate at which objects fly around the sun in the area is 20 km / s.This one revolution of the main belt asteroids spend three to nine Earth years.For most of them characterized by a slight inclination of the orbit to the ecliptic plane - 5-10º.However, there are also objects that the flight path of the plane of rotation of the Earth around the world more impressive angle of up to 70º.This characteristic was the basis of the classification of asteroids into two subsystems: the flat and spherical.The inclination of the orbits of objects of the first type is less than or equal to 8º, secondly - more than the specified value.
Occurrence
In the nineteenth century the scientific community has been widely discussed hypothesis about the deceased Phaeton.The distance from Mars to Jupiter quite impressive, and there could pass the orbit of another planet.However, such ideas are considered obsolete today.Modern astronomers adhere version that the place, where the asteroid belt, planet simply could not occur.The reason Jupiter.The gas giant is still in the early stages of its formation has a gravitational effect on the region lying closer to the sun.He attracted a part of the substance of the zone.Not captured by Jupiter bodies were scattered in different directions, protoasteroidov speed increased, the number of collisions.As a result, they are not only not to increase weight and volume, but become even smaller.In the course of such transformations the likelihood of a planet between Jupiter and Mars began to vanish.
constant influence
Jupiter and today "does not leave at rest" asteroid belt.Its powerful gravity causes changes in the orbits of some of the bodies.Under her influence were the so-called no-go areas where the asteroid almost none.The body flies here because of a collision with another object, is pushed out of the zone.Sometimes this orbit is changing so that it leaves the asteroid belt.
more rings
main asteroid belt is not alone.On its outer edge placed two less imposing such education.One of these rings is located directly on the orbit of Jupiter and is represented by two groups of objects:
- «Greeks" ahead of a gas giant about 60º;
- «Trojans» behind the same number of degrees.
characteristic feature of these bodies is the stability of their movement.It is possible due to the location of asteroids in the "Lagrange points", which are balanced by the gravitational effects on all these objects.
Despite the relative proximity to the Earth, the asteroid belt is insufficiently studied and holds many mysteries.The first of these, of course, is the origin of small bodies of the solar system.There is a suggestion in this regard, although they sound convincing enough, it has not yet received a clear confirmation.
raise questions and some features of the structure of asteroids.It is known, for example, that even belt objects related in some respects quite different from each other.The study of the characteristics of asteroids and their origin is necessary both for understanding the events preceding the formation of the solar system as we know it, and for constructing theories about the processes occurring in remote areas of space systems of other stars.
