solar system - the only one available for us to directly study the planetary structure.The information obtained on the basis of research in this area of space, used by scientists to understand the processes occurring in the Universe.They make it possible to understand how our system originated and similar to her, what kind of future awaits us all.
classification of planets in the solar system
Research astrophysicists allowed to classify the planets of the solar system.They were divided into two types: Earth-and gas giants.For terrestrial planets are Mercury, Venus, Earth, Mars.Gas giants - is Jupiter, Saturn, Uranus and Neptune.Pluto in 2006 received the status of dwarf planet, and refers to the objects of the Kuiper Belt, differs in its characteristics from the representatives of both these groups.
Characteristics of terrestrial planets
Each type has a set of features associated with the internal structure and composition.High average density and the prevalence of rock and metal at all levels - these are the main characteristics that distinguish the terrestrial planets.Giants in contrast, have low density and are composed primarily of gas.
All four planets have a similar internal structure: a solid crust is viscous mantle, enveloping the core.The central structure, in turn, is divided into two levels: a liquid and a solid core.Its main components - a nickel and iron.The mantle differs from the core predominance of silica and manganese.
sizes of the planets of the solar system related to terrestrial, distributed in such a way (from low to high): Mercury, Mars, Venus, Earth.
Aerial shell
Earth-like planets already in the first stages of its formation was surrounded by an atmosphere.Initially, the predominant part of its carbon dioxide.Change the atmosphere in the world contributed to the emergence of life.For terrestrial planets are so cosmic bodies, surrounded by an atmosphere.However, among them there is one who has lost his air cover.This Mercury, whose mass is not allowed to keep the primary air.
closest to the Sun
The smallest terrestrial planet is Mercury.His research is difficult being close to the sun.Since the beginning of the space age data on Mercury were received only from two devices, "Mariner-10" and "Messenger".On this basis, we managed to create a map of the world and identify some of its features.
Mercury really possible to recognize the smallest terrestrial planet: its radius is slightly less than the 2.5 thousand kilometers.Its density is close to Earth.The ratio of the size of this indicator gives reason to believe that the planet is largely composed of metal.
Movement Mercury has several features.Its orbit is highly elongated: at the farthest point away from the Sun is 1.5 times greater than the nearest.One revolution of the planet around the star does in about 88 Earth days.Thus for this year Mercury has time to turn around its axis only half.Such "behavior" is not characteristic of the other planets of the solar system.Presumably the initially more rapid deceleration motion was caused by tidal influence of the sun.
Beautiful and terrible
For terrestrial planets are both the same and different cosmic bodies.Similar in structure, they all have features that make them impossible to confuse.The closest to the Sun, Mercury is not the hottest planet.It even has sections, always covered with ice.Venus, the next in proximity to the star, characterized by higher temperatures.
Named after the goddess of love, the planet has long been a candidate for habitable space objects.However, the first flights to Venus refuted this hypothesis.The true essence of the world hides a dense atmosphere composed of carbon dioxide and nitrogen.This air environment contributes to the development of the greenhouse effect.As a result of the planet's surface temperature reaches 475 ° C.There thus can be life-threatening.
second in size and distance from the Sun, the planet has a number of features.Venus - the brightest spot in the night sky after the Moon.Its orbit is almost a perfect circle.Around its axis it moves from east to west.This trend is not typical of most planets.Orbit around the Sun, it makes for a 224.7 Earth days, and around an axis - for 243, that is a year shorter than the day here.
third planet from the Sun
Earth is unique in many ways.It is located in the so-called habitable zone, where the sun's rays are not able to turn the surface of the desert, but warm enough to the planet is not covered with ice.Slightly less than 80% of the surface takes the oceans, forming together with rivers and lakes, the hydrosphere, the absence of the other planets of the solar system.
formation of a special Earth's atmosphere consisting mainly of nitrogen and oxygen, contributed to the development of life.As a result, increasing the concentration of oxygen formed the ozone layer which, together with the magnetic field protects the planet from the harmful effects of solar radiation.
only satellite of the Earth
moon has quite a serious impact on the Earth.Our planet has got a natural companion almost immediately after its formation.The origin of the Moon remains a mystery, although in this respect there are some plausible hypotheses.The satellite has a stabilizing effect on the tilt of Earth's axis, and also slows down the planet.As a result, each new day becomes a bit longer.Slow down - a consequence of the tidal influence of the Moon, the same force that causes the tides in the ocean.
Red Planet
Asked what the terrestrial planets were studied after our best to always be a definite answer: Mars.Because of the location and climate of Venus and Mercury studied to a much lesser extent.
If you compare the sizes of the planets of the solar system, Mars is on the seventh place in the list.Its diameter - 6800 km, and the weight is 10.7% from the similar parameter of the Earth.
on the red planet highly rarefied atmosphere.Its surface is covered with craters, and here you can see the volcanoes, valleys and glacial ice caps.Mars has two moons.The closest to the planet - Phobos - is gradually reduced in the future will be broken gravity of Mars.For Deimos, on the other hand, is characterized by the slow removal.
idea about the possibility of life on Mars has been around for more than a century.Recent studies conducted in 2012, found on the red planet organic matter.It has been suggested that organics could bring to the surface the rover from Earth.However, studies have confirmed the origin of the material: its source - the red planet itself.However, an unambiguous conclusion about the possibility of life on Mars without additional research can be done.
For terrestrial planets are closest to us on location space objects.And because they are by far the best known.Astronomers have already discovered more extrasolar planets, presumably as belonging to this type.Of course, every such discovery increases the hope of finding life outside our solar system.
