Knew IAU planet as a celestial body orbiting a star or the remnants of a star in the sky , which is large enough to become a form of rounded approximation by the force of attraction , but it is not huge enough to score occurrence of thermonuclear fusion and can be cleared its orbit of planetesimals or asteroids . [a]   The word " planet " is old and linked to several aspects of the historical , scientific, and religious fairy . Many of the ancient civilizations of the planets were considered sacred symbols or divine messengers . Some still believe in our current knowledge of astrology which is based on the impact of the movement of the planets on human life , although | scientific objections to the results of this science . But people's ideas about the planets changed completely with the development of scientific thought in the modern era and the accession of a number of different motives . To date there is no standard definition of the meaning of the planet. In 2006 , ratified the International Astronomical Union 's decision to formally define the meaning of the planets in the solar system . Has met this definition is widely welcomed and scathing criticism at the same time , this definition is still controversial among some scientists . Ptolemy was thought that the Earth is the center of the universe and all the planets revolve around it in a circular orbit . Although the idea of putting all the rotation of the planets around the sun many times , they did not prove the scientific evidence , but in the seventeenth century when he managed the Italian scientist Galileo Galilei monitoring of the solar system through a telescope astronomer who invented . Has proved to the world the German Johannes Kepler after careful analysis of the data astronomical observations that planetary orbits are oval rather than circular . With the development of monitoring devices , astronomers discovered that all the planets , including Earth , revolve around their axes , but slightly awry , and is characterized by some common characteristics , such as the formation of ice on the poles and passing several classes per year . With the start of the space age , he discovered the man , after examining soil samples from the planets across devices space probe , several characteristics shared between the Earth and the other planets , such as the nature of the volcanic and the presence of hurricanes and Altktonaat ( the process of distortion that change the shape of the Earth's crust updated continents and mountains ) and even hydrology. Since 1992 , after the discovery of hundreds of extrasolar planets (ie, spin it around other stars ) , scientists realized that all the planets in the Milky Way shares many characteristics with the planet . Planets are divided generally into two main types : the major planets , the giant planets composed of low-density gas , and smaller planets, rocky nature , such as the planet Earth . According to the definitions of the International Astronomical Union , consisting of eight solar system planets . The order of these planets according to their distance from the sun begins four rocky planets Mercury, Venus, Earth and Mars , then the gas giant planets Jupiter, Saturn, Uranus and Neptune . It also features the solar system on the five dwarf planets are: Ceres and Pluto ( which was previously classified Ktasa planet in the solar system ) and Mikmik and Haumea and Eris . And it's all of those planets, the moon and one or more with the exception of Mercury, Venus, Ceres and Mikmik . By March 2009 , the number of planets discovered outside the solar system planets 344 and their size varies from gas giant planets to smaller planets with rocky nature . 
Evolved the idea of the planets from time immemorial ; where she is at last sacred Nujoma car so we now have a detailed scientific picture of her . Currently has expanded its concept to include hundreds of planets outside our solar system . Has contributed to the ambiguity of the definition of planets in increasing controversy and scientific debate on the subject . In ancient times, astronomers noted how certain lights applicable in the sky in the direction of a particular star . He was the ancient Greeks on those lights "πλάνητες ἀστέρες" (planetes asteres ( in the sense of stars car) or "πλανήτοι" (planētoi ( in the sense only car ) and it derived the word " planets " present .  [ 5 ] This was the belief prevailed because the Stars The planets seemed to the people of the planet Earth as if it were a day hovering around the earth ,  and was innate concept is that the planet is consistent and stable and immobile
The Babylonian civilization is the first known civilization was able to reach to the theory of operation for the planets. The Babylonians lived in Mesopotamia ( now Iraq ) in the first and second millennia BC . The " board Omsadoka Babylonian Venus ," the text of the oldest astronomical staying for a copy of the planets discovered in the seventh century BC, which is a list of some notes for the movement of the planet Venus probably dating back to the beginning of the second millennium BC . The Babylonians were the founders true for Western astrology .  There is a text called Enuma anu enlil written during the era of the Assyrian Neo in the seventh century BC , [8 ] and this text contains some spells relating to certain celestial phenomena , including the movement of the planets .  the Sumerians , the Babylonians , and they are the successors are considered among the leading civilizations and return them credit for the invention of writing , he knew at least Venus in 1500 BC . AD . 
Ancient Greek civilization and even the Middle AgesEdit
Cosmic order is derived from the ancient Greek civilization, Babylonian , where the ancient Greeks in the acquisition of astronomical science of the Babylonians in about the year 600 BC . AD . Such as planetary science and towers .  By the sixth century BC was the Babylonians had made progress in astronomical science than what we achieved the Greeks . </ Ref> The proof of this is that the oldest sources of Greek , such as the Iliad and the Odyssey missed out any mention of the planets . By the first century BC , the Greeks began to develop mathematical theories to identify the positions of the planets . These theories, which relied on engineering and Babylonian arithmetic is not in the end overtake the Babylonian counterparts in terms of complexity and comprehensiveness , as in most reliable satellite movements that are observed by the naked eye from the surface . Those theories have reached the ideal image in the book of Ptolemy : Almagest , written in the second century AD . This was considered a model written by Ptolemy is the main reference in the Western world , which has been riding the superiority of books on astronomy , and remained on this position for 13 centuries . The Greeks and Romans knew of seven planets , and they believe that the planets revolve around the Earth , according to the laws of Ptolemy . The ranking , according to the laws of Ptolemy , starting from the ground as follows: Moon and Mercury, then Venus , then the Sun and then Mars and then Jupiter and Saturn .  [ 13] [14 ]
When the Arabs planets is the old name of the planets that you see from the ground roving among the stars . Has been named "car" because the ancient Arabs were called all the points gleaming in the sky as " planets ." But they noticed that some of them are constantly moving across the sky is spin Planetarium resulting from the earth's rotation around itself . Therefore, the animated ones named as " planets " (which is now called " planets " ) and fixed the " fixed planets " (which is now called "stars" ) . Arabs did not consider them gods Kaligriv although they Azmoha , a buyer taking his name because he bought himself to greatness . It was the buyer and Venus have special significance for severe Maanama
Perhaps the five planets that you see with the naked eye has been known since time immemorial , has had a severe impact of those planets on the legends and cosmic science, religious and ancient astronomy . With the development of scientific knowledge , change the concept of the word " planet " than just a body to wander in the sky ( about a certain star ) to the body revolves around the earth (or so it was thought old ) , that we discovered in the sixteenth century that the planets revolve around the sun , and so With the ratification of the model of the solar center for " Copernicus " and " Galileo " and " Kepler ."  when it was discovered moons of the Jupiter and Saturn in the seventeenth century , they used the word " planet " and " moon " are used interchangeably , although the word " moon " are becoming prevalent in the eighteenth century .  and by mid-century the nineteenth century, the number of planets discovered too , where it was called the scientific community on any body revolves around the sun directly name " planet " .
In the nineteenth century , scientists realized that the objects discovered recently and which is classified as a planet for half a century (eg , Ceres and Pallas Vista) is quite different from the traditional planets . These objects swim in the same region of space between Mars and Jupiter ( the asteroid belt ), but much smaller than the mass of the planets , and it has been categorized as asteroids . In the absence of any formal definition of the word " planet " , has been customary that the planet is any object that has a very large orbit around the sun . Because of the huge difference in size between the asteroids , planets and depression after the flame of enthusiasm after the discovery of the planet " Neptune " in 1846 , it were not there is an urgent need to develop a formal definition . 
However, it was the discovery of Pluto in the twentieth century . The monitoring showed initial Pluto to be the largest of the Earth ,  , making it classifies Ktasa planets in the solar system . To be discovered later that the smaller of the ground much , but in 1936 most likely " Raymond Littleton " that Pluto could be a satellite distracted from the planet Neptune ,  while likely " Fred Whipple " in 1964 that Pluto may be guilty . [ 20 [ However, it is due to the fact that Pluto is still larger than all known asteroids as it swims alone in space ,  has been retained as a planet until 2006 . Period was characterized by the nineties and early third millennium discovery of an enormous iceberg of celestial bodies that resemble the solar system called ( Kuiper belt ) . Like Ceres and many asteroids discovered before him , he discovered that Pluto is only a small body floating in the space between the thousands of other objects . Was supported by many astronomers to exclude Pluto from the list of planets , especially after the discovery of several bodies similar to him in size. The discovery of what is known as the tenth planet named " Iris " and the very large in size to the subject of re- definition of the planets to mind again . The International Astronomical Union issued a definition of the term " planet " in 2006 . The shrinking number of planets to eight largest planets in terms of size , which was able to give up the orbit of the asteroid ( Mercury, Venus, Earth , Mars, Jupiter, Saturn, Uranus and Neptune ) , and added another list includes dwarf planets ( Ceres and Pluto and Eris ) .  Planets in the period between 1930-2006 Mercury Venus Earth Mars Jupiter Saturn Uranus Neptune Pluto
In 1992 , scientists announced " Alexander Wolfscan " and " Del Fraal " the discovery of planetary systems around a star Tareq ( radiant star ) PSR B1257 + 12.  This is the first discovery of an actual group of planets orbiting a star . In the sixth of October 1995 , it was announced , " Mitchell Mayor " and " Didier Cuelloz " from the University of Geneva for the first actual discovery of a planet outside our solar system orbiting a normal star in another major , and this is called the star (51 Pegasi). The discovery of other planets outside our solar system to give more of a mystery to the definition of the term planet , or more precisely when the planet becomes a star. Many of the known planets outside the solar system is larger than the size of Jupiter several times , as it is close to the size of celestial objects known as " brown dwarfs " .  Those brown dwarfs are stars, in general, due to their ability to integrate heavy hydrogen ( deuterium ) . While the star which is estimated at as much as 75 times the size of Jupiter have the ability to integrate hydrogen , the star , which is equivalent to the size of Jupiter 13 times only have the ability to integrate heavy hydrogen ( deuterium ) . But worth mentioning here is the scarcity of heavy hydrogen has stopped most of the brown dwarfs from the merger of heavy hydrogen ( deuterium ) before detectable long ; making it similar to a large extent with the giant planets .  With the discovery of the " Kuiper belt " great and many orbs disc Figure sporadic in the late nineties and early century atheist century, was the launch of the title of planet X on many planets , such as Koor and 90377 Iris in many media , but none of them had not recognized scientifically until now , and this despite the fact that Iris is now classed as a dwarf planet .
Definition of a planet which is located outside the solar system
In 2003, the workshop on planets outside the solar system of the International Astronomical Union to provide a statement on the definition of the term " planet " , which included the following working definition , which focuses mainly on the difference between planets and brown dwarfs :  Dwarf planets in 2006 - Ceres Pluto Haumea Makemake Eris
Planets are celestial bodies that less mass true for mass necessary for the occurrence of nuclear fusion thermal hydrogen heavy (which is currently estimated at twice the mass of Jupiter 13 times and so for objects that have the abundance isotope same sun  ) that revolves around a star , or the remnants of a star in the sky (regardless of the method of composition ) . It must be the minimum block size orb , which is located outside the solar system is equal to that of the solar Bkwakb to reach this rank offense to the planet , as well as there are types of planets that do not follow or groups of stars called rogue planets . The objects without stellar mass in excess of the true mass necessary for the occurrence of thermonuclear fusion of hydrogen heavy- called " brown dwarfs " , regardless of their location or method of composition . The orbs floating in space for gatherings stellar small and less mass true for mass necessary for the occurrence thermonuclear fusion of hydrogen heavy no longer " planets " , but it can be called " brown dwarfs secondary " ( or any other name more appropriate ) .
The shot to the use of this definition among astronomers when publishing their findings about planets outside the solar system in scientific journals . [ 27] Although this definition is temporary , it still retains its place as the best definition until further notice . However, it did not address the controversy about the Rebel minimum mass ,  and thus enables the definition of Rebel avoid controversy about the planets of the solar system , and also did not comment on things that revolve around the dwarf planets , such as: 14:00 1207 b .
Definition in 2006Edit
The special theme raised the minimum mass during the meeting of the General Assembly of the International Astronomical Union in 2006 , and after a lot of discussions and rejected a proposal , the General Assembly approved the union to vote in favor of the resolution defines the planets of the solar system : 
A celestial body that is (a) in orbit around the Sun, (b) has sufficient mass for its self-gravity to overcome rigid body forces so that it assumes a hydrostatic equilibrium (nearly round) shape, and (c) has cleared the neighbourhood around its orbit.
According to this definition, the solar system consists of eight planets . The bodies to which it applies conditions are the first and second only (eg , Pluto and Makemake and Eris ) Vsnaft as " dwarf planets " , provided that the satellites belonging to other planets . Has a committee of the International Astronomical Union to provide another definition included a larger number of planets ; since it did not include the requirement (c ) .  and after numerous discussions , it was agreed to exclude those orbs and classified as " dwarf planets " . [ 30 and this definition is based mainly on the theories of the formation of planets , which managed the planets during the formative stages of the evacuation of the first orbit of other celestial bodies smaller . It describes the world of astronomy , " Steven Soter " , saying : 
The end product of secondary disk accretion is a small number of relatively large bodies (planets) in either non-intersecting or resonant orbits, which prevent collisions between them. Asteroids and comets, including KBOs (definition needed), differ from planets in that they can collide with each other and with planets.
After the vote, which took place during the General Assembly of the International Astronomical Union in 2006 , There was considerable debate and bitter debate about the definition, [ 32 ] [ 33 ] Indeed, some astronomers have stated that they will not use it at all.  and concentrated this dispute about the condition (c ) to vacate your orbit , where many scientists are likely to delete this condition, and that what is now called " dwarf planets " must be covered by the definition of the term planet . The conference will be held next International Astronomical Union in 2009 , which can amend the definition of which in 2006 or add planets outside the solar system. The non- scientific level , Pluto has won the attention it deserves and considered a planet since its discovery in 1930 . Iris was reported in the media after he discovered the tenth planet in the solar system , sparking the attention of the media and public opinion strongly when Ranked among three other planets as a " dwarf planet " . 
The following table shows the celestial bodies in the solar system planets that were considered in the past : Notes orbs The sun and moon are classified in antiquity as the planets, according to the definition used at the time. Io , Europa and Ganymede and Callisto 's four largest moons belonging to the buyer and are known as the " Galileo satellites ' relative to the discoverer " Galileo Galilei " . Has been referred to as " satellites Madekkean " relative to its patrons Medici family . Titan [b] and Aaabitos [c] and Rea [c] and Tethys [d] and Dion [d] five of the largest satellite of the planet Saturn . The scientists discovered them Christian Higgins and Giovanni Domenico Cassini . Series [e] and the Palace and Juno and Vista has been known since the first asteroids discovered in the period between 1801 and 1807 that have been reclassified again as asteroids in the fifties of the nineteenth century .  have been classified Ceres after it as a dwarf planet . Istria and Hebe and Iris and Flora and the Mets and Hygeia and Barthenob , Victoria and Egeria and Irene and Aonomia was discovered more asteroids in the period between 1845 and 1851. Has resulted in the discovery of a large number of stars to do astronomers re- classified as asteroids and the move has been widely accepted by the year 1854.  Pluto [f] a orbs that fall after the planet Neptune has a semi- essential axis beyond Neptune . In 2006, Pluto was reclassified as a dwarf planet .
I miss the names of the planets in the Western civilization from the Romanian traditional names , which are derived mainly from the Greeks and the Babylonians . In the civilization of ancient Greek , was the largest exporters of light , namely the sun and the moon the name " Helios " and " Celine " and fired at the farthest planet , " Pinon " any " radioactive " and then " Pithon " any " brilliant ," The Red Planet has named it " Baaruiz " any " fiery planet "As more planets shine has named it " Fosforos " any " Mr light , " the last of those planets floating in open space has been termed " Stalpon " any " of the planet with a flash . " The proportions of the Greeks also these planets to the gods of Mount Olympian holy , it has been the launch of my name " Helios " and " Serene " on the planets and the gods , the " Pinon " It was a name sacred and dedicated to the god of " Chronos " , one of the mighty men who ruled the world before the gods of Mount Olympian holy also believes ancient mythology , was " Pithon " a name sacred to the god " Zeus " ; , the son of the King, " Kronos " who succeeded him in ruling the world , but " Byrus " it was a name sacred to the god " Ares " is the son of " Zeus " and the god of war at the same time , the " Fosforos " it was a sacred name for God , " Aphrodite " goddess of Love , and the " Hermes " messenger of the gods and the god of science and business acumen has been the ruler of the planet , " Stalpon " .  previously Babylonians Greeks in the launch of the names of the gods on the planets. It has launched the Babylonians on the planet " Fosforos " this name after the name of the goddess of love in Babylon, Ishtar and fired on the planet " Baaruiz " the name of the god of war " Nergal " and fired on the planet " Stalpon " the name of the god of wisdom , " Napo " and fired on the planet " Pithon " the name of their God, the greatest " Marduk " .  there are many similarities between the methods of the launch of the names of the planets among the Babylonians and Greeks .  Although the translator were not as accurate as it should be . For example , was the god of war, when the Babylonians called " Nergal " , so the Greeks called it " Ares " . However , Unlike " Ares " , the " Nergal " was also the god of evil and hell . [ 40 ] at the present time , most people in the western world know the planets by their names are derived from the names of the gods of the mountains Olympian Greeks . While still Greeks are currently using ancient Greek names of the planets , most of the other European peoples used the names Romania ( or Latin ) , due to the vulnerability of these peoples Romanian Empire and the Catholic Church later . Romans and Greeks descended from Indo-European origins , and they revere the gods one by different names , but the Romans did not have the creativity and literary fiction writers who has brought the Greeks to their gods . In the recent period of civilization Romanian old , borrowed many writers Romans from the creators Greeks stories of historical and applied it to their gods , to be mixed up between these names and such . [ 41] when he studied Roman astronomy Greek , they fired on the planets names of their gods : they called the name " Mirkorius " on " Hermes " and " Venus " on " Aphrodite " and " March " on " Ares " and " Opetr " on " Zeus " and " Saturnos " on " Kronos ." After the discovery of other planets in the eighteenth century and nineteenth centuries , has been named in the same way ; , where they name " Uranus " instead of " Uranus " and " Neptonos " instead of " Poseidon ." I think that some of the Roman gods , which was launched seven names on the planets they take turns to take care of the affairs of the world , a belief probably originated in the Old Babylonian civilization , but the evolution of ancient Egypt in the Greek . This was the rotation according to their belief begins to Saturn and then followed by the buyer then Mars and then the sun , then Venus , then Mercury and finally the moon ( and this arrangement far to near ) . [42 ] Therefore , it was the first day begins with Saturn ( the first hour ) and the second day begins with the sun ( five o'clock Twenty ) and the third day of the moon ( Forty-ninth time ) and then Mars Ftard a buyer and finally flower . Due to label each day as the god who starts , this is also the order of days of the week according to the Roman calendar after the rejection of Nundinal cycle and continues to this label has not changed in a lot of modern languages . [ 43 ] For example , Sunday ( Sunday ) and Monday ( Monday ) and Saturday ( Saturday), is a direct translation of the names of Romania . In English , the rest of the week was named as follows : Tuesday Sunday Tiw and Wednesday Wednesday Wóden and Thursday Tuesday Thunor and Friday Friday Fríge, while the names of the gods of the Anglo -Saxons were similar or are the names of the planets Mars, Mercury , Jupiter and Venus respectively . Because the Earth did not accept classified as a planet , but in the seventeenth century ,  they have not called on the name of one of the gods ( and the same applies to the sun and moon in English , at least ) . Was derived the name of the land since the eighth century of the word Anglo-Saxon erda which means ground or soil and used for the first time in writing as the name of the airspace of the lighting probably around the year 1300 . [ 44 ] [ 45 ] The planet Earth is the only planet that is not derived its name from the ancient Greek mythology Romania . There are still many languages Romanian word is used Romanian ancient terra sense of the earth ( or a word derived thereof) which was used an old sense of the land ( the word counter word for sea ) .  However, the language is romantic uses her own original . While retaining the Greek word original Γή (Ge or Yi) and Germanic languages , including English , using a word derived or taken from the floor Germanic origin ertho ( earth) and its counterpart in English Earth and German Erde , Dutch Aarde , and the Scandinavian Jorde.  used non-European cultures other systems in the naming of planets. India , for example, use a naming system depends on the calendar , " Navagraha " Indian origin , and it is called the sun " Syria " and the moon " Chandra " Mercury " Buddha " Venus " Huckra " Mars " Mangala " and Jupiter [ Braspata | " Template: Iast Braspata " ]] The Saturn it is called a " Shani " . The named Alakdtan Aalghemceka uplink and downlink in association phenomena eclipses and eclipse the " Rahu " and " Ketu " . As China and East Asian countries affected by the civilization of China (eg , Japan , Korea, and Vietnam) , it has been used a system depends on the elements of the five Chinese : water (Mercury ) , metal ( Venus ) , fire ( Mars ) , wood ( Jupiter ) and earth (Saturn ) .
The formation of planetsEditDoes not know exactly how to be planets. The common theory is that these planets may have resulted in the collapse of the gaseous nebula consists of a high to a disk of gas and dust . It assumes that theory that the nebula was composed of a primary star in the center surrounded by protoplanetary disks of rotary . Through the accumulation of ( the process of sticky collision ) dust particles in the disk steadily accumulate mass to form the largest ever of bodies . And accumulated many of the dust particles in the disk composed celestial objects Stern enormous size. And the effect of topical concentrations formed blocks , known as " embryonic planets " , has helped those planets micro acceleration in the process of accumulation through attracting many other materials resulting from the central gravity of rotation. The increased density of such concentrations that exploded from within by gravity consisting of those protoplanets . [ 47 ] and after that hit the planet diameter larger than the diameter moon 's land , begins to assemble atmosphere extended ; leading to a growing ability to attract planetesimals by force disability of the atmosphere . [ 48 ]
Artist impression about the protoplanetary disk
When I grow up star Initial even a degree of ignition to be the star of a real , it expels the disk rest inside to the outside due to evaporation photosynthesis and solar wind and Poynting-Robertson drag and many other factors . [ 49 ] [ 50 ] and after that , there could be some protoplanetary which still revolves around the star , or about each other , but with the passage of time will collide with each other made up a planet and one big or absolute material absorbed by the planets initial significant other or planets incomplete.  and will grow those bodies to be able to attract many of the objects that orbit in its orbit until it reaches its final form Kkwakb incomplete. In the meantime , you can turn protoplanetary which did not explode to the satellites belonging to other planets through the gravitational central or continue to spin in the belts of other objects to reach its final form Kkwakb dwarf or just small objects in the solar system . The effects of the planets embryonic effective ( and radioactive decay ) , will cause the heating of the planet , causing the developing melting at least in part . It starts the inner part of the planet is changing to become more intense.  and lose planetary other most Ghazadtha by this accumulation , but these gases are lost can be compensated through the gases from the atmosphere and comets other . [ 53 ] ( The planets smaller will lose any gas obtained by the escape of these gases ) . After the discovery and follow-up of several planetary systems around stars outside our solar system , this analysis has become subject to review or change altogether. At present , the level of metal ( an astronomical term describing the extent of the concentration of the chemical elements , which increases its atomic number 2 _ atomic number of helium _ is defined by the possible presence of planets a star or not. [ 54 ] Therefore, the possibility of a planetary system around the star mineral-rich population II over the possibility of a planetary system around the star metal poor population I.
According to the current definition of the International Astronomical Union , there are eight planets in the solar system . And arranged as follows according to their distance from the sun to the nearest farther :
[82 ] Mercury  Venus  Earth [ 85 ] Mars [ 86 ] buyer [ 87 ] Saturn [ 88 ] Uranus  Neptune
Jupiter is the largest planet in the solar system ; , where the mass times the mass of the Earth 318 times , while the smallest is the planet Mercury , where the mass of the planet twice the mass of 0.055 times. Can be classified as planets of the solar composition as follows :
Rocky planets ( rocky planet ) : includes Earth-like planets ; which consists essentially of rocks . These planets are Mercury, Venus, Earth and Mars . Gas giant planets ( Jupiter -like planets ) : includes gas giant planets , which consists mainly of gaseous material is higher than the rocky planets in terms of size . These planets are Jupiter, Saturn, Uranus and Neptune . There is a secondary category falls under the category of gas giant planets , a giant icy planets , which includes a planetary Uranus and Neptune . Featuring the planets from gaseous planets are small for gaseous planets and an out of hydrogen and helium in the atmosphere , in addition to increasing the proportion of rock and ice which significantly. The characteristics of the planets
The name of the planet's equatorial diameter
[a] Orbital radius ( astronomical units ) orbital period ( in years ) the tendency to the equator of the sun ( mainly ) the amount of decentralization of the orbit period of rotation around the axis (days) Number of satellite loops atmospheric composition of the planet Mercury 0.382 0.06 0.39 0.206 0.24 3.38 58.64 - No No rocky planets Venus 0.949 0.82 0.72 0.007 0.62 3.86 243.02 - no carbon dioxide CO2 and nitrogen N2 rocky planets Planet Earth
[b] 1.00 1.00 1.00 1.00 7.25 0.017 1.00 1 No nitrogen N2 and oxygen O2 rocky planets Mars 0.532 0.11 1.52 1.88 0.093 5.65 1.03 2 No carbon dioxide CO2 and nitrogen N2 rocky planets Buyer 11,209 317.8 5.20 11.86 6.09 0,048 0.41 49 no H2 hydrogen and helium He gas giant planets Saturn 9.449 95.2 9.54 29.46 5.51 0.43 0.054 52 There H2 hydrogen and helium He gas giant planets Uranus 4.007 14.6 19.22 84.01 6.48 0.047 -0.72 27 There H2 hydrogen and helium He gas giant planets Neptune 3.883 17.2 30.06 164.8 6.43 0.67 0.009 13 There H2 hydrogen and helium He gas giant planetsFor the planet, see the article by the planet to get the full value.
Crystal Clear app kdict.png detailed article : exoplanet
Was the discovery of the first planet outside our solar system orbiting a star with another major in Sixth of October in 1995 when he declared all of the " Mitchell Mayor " and " Didier Cuelloz " Professors at the University of Geneva discovered a planet orbiting a star outside a sequential key (51 Pegasi). This was the size of most of the planets that have been discovered outside the solar system in February 2009 , and of which there are 342 planets closer to the size of Jupiter or larger than him , in spite of the monitoring of the planets , ranging in size from less than the planet Mercury and is the largest of Jupiter several times . [ 56 ] In addition, the smaller planets have been discovered outside the solar system to the present day is a group of planets that have been detected orbiting a star burning effects of the so-called group -star Tariq , such as PSR B1257 +12.  / has been discovered about 12 extrasolar planets of mass twice the mass of Earth increased by between 10 and 20 times, and that such planets orbiting the stars Mu Arae , cancer 55 and GJ 436.  was launched on these planets name " Alneptunaat " due to the approaching mass of the mass of the planet Neptune ( which is twice the land mass 17 times) . [ 59 ] that there is another category of new planets called " land great ," which is a rocky planets larger than the Earth much but smaller than Neptune or Uranus . </ ref> it should be noted that it was the discovery of nearly six land great even to this day , a planet Glez 876 b , which amounts to twice the mass of the Earth six times, [ 60 ] and the planet OGLE-2005-BLG-390lb and Moa-2007-BLG-162Lb two planets Geledian been discovered by lenticular micro -gravity . [ 61 ] [ 62 ] among these planets six also planet COROT - Exo -7 b , a planet estimated diameter twice the diameter planet by 1.7 times (which thus have smaller land the great undiscovered until now ), but the estimated distance orbit to 0.02 astronomical units only which means that its surface is soluble at temperatures between 1000-1500 degrees Celsius .  Finally, there are planets of these planets orbiting red dwarf Gliese 581. The mass of Gliese 581 d twice the mass of Earth increased by 7.7 times ,  while the mass of Gliese 581 c five times the mass of Earth , which was initially thought to be the first rocky planet has been discovered can be no life on it. [ 65 ] however , revealed detailed studies it was close to the star of his very much to make it invalid to establish the life of him , while the planet Gliese 581 d farther planet in the group despite the fact that Tksh cooler than the Earth's weather , it is possible that life exists it if its atmosphere contains greenhouses gases is sufficient.  from here , it is clear exactly what if the newly discovered large planets similar to the gas giant planets in the solar system are similar or completely different type is not yet known , such as the planets carbon or ammonia giant planets . In general , spin some planets that have been discovered recently , known as hot Jupiters , close to their parent stars in circular orbits to some extent. Thus, the stellar radiation they received a greater proportion of those that reach the giant gaseous planets in the solar system which leaves the door open for argument about whether these planets are all of one kind or not. It is also likely the existence of a class of hot Jupiters , called Alcathonah and planets that orbit close to their star to the extent that its atmosphere was burned by the stellar radiation . While many of the hot Jupiters are now experiencing the loss of its atmosphere , as happened in 2008 , not the discovery of a planet Kathona real .  In fact, the discovery of more scientific facts detailed about planets outside the Total Solar requires the introduction of a generation New devices , including the space Telescope . This being the spacecraft COROT recently current research on the different level of brightness on the stars because of the rotation of the planets around it. Well, there are many projects have been put forward for the production of space telescopes to search for planets outside the solar total that are similar in mass to the ground . Among these projects, the project Kepler Mission NASA's Project Terrestrial Planet Finder and programs Space Interferometry Mission of Darwin 's for ESA and PEGASE 's for CNES.  as well and is a New Worlds Mission of devices that can be used in conjunction with the telescope , " James Webb " space . However , it is not sure there are sources to finance these projects . However, the first spectrum of planets outside the Total Solar loomed on the horizon was in February of 2007 ( planet HD 209458 b and HD 189733 b).   The frequency of the appearance of rocky planets is one of the variables in the equation , " Drake ," which calculates the number of intelligent civilizations that have and have the ability to communicate in our galaxy . [71 ]
Suggests a lot of simulation models by computers depicting formation of planetary systems , and the stars that some of the objects that have a mass similar to the mass of the planets can be launched in the space of the stars.  Some scholars have attempted to prove that roams the deep space of such celestial bodies should be classified under the category of " planets " . However , others of them say it is possible to form stars with a small block . [ 73 ] While the definition of planets outside the solar system adopted by the International Astronomical Union was not a clear opinion on this issue . In 2005, astronomers announced the discovery of the body Cha 110913-773444 , the smallest brown dwarf has been discovered so far and has seven times the mass of Jupiter . As it is , while the discovery was not orbiting a star in orbit , it is considered a brown dwarf secondary depending on what came in the definition of the International Astronomical Union . [ 73 ] and in a short period in 2006 , astronomers found a subset of such objects , a Oph 162225 - 24515 , which called finders planemos or " planetary Group ." However, the recent analysis of these celestial explained that the mass of each of which is larger than the mass of Jupiter by 13 times, as much as any mass Gazzmin Bnyen . [ 74 ] [ 75 ] [ 76 ] General characteristics of the planets
Although each planet has unique physical characteristics that distinguish it from other planets, there are a number of general characteristics shared by the entire planets. The spotted some of these characteristics, such as rings or natural satellites, planets in the solar system just yet, while others waivers where planets outside the solar total.
Crystal Clear app kdict.png See also : Kepler's laws
Orbit 250 pxThe compared to the orbit of the planet Neptune, Pluto's orbit . Note elongation orbit of the planet Pluto for Neptune ( decentralization ) and the angle formed by the large orbit with solar (tilt ) .
All the planets revolve around stars . For the solar system , all the planets revolve in the same direction , which rotates by the sun. But science has not reached yet know whether planets outside the solar total follow the same pattern or not. Called the period in which the planet one session in the name of its orbit duration astronomical or astrological year . [ 77 ] and rely astronomical year of the planet over the distance from the star that followed . Whenever after the planet from its star , the greater the distance traveled by the rotation in orbit around this star and Btat speed of rotation around it, due to the weakness of the gravitational influence of the star it. Because the orbits of the planets are all incomplete rotation , varying the distance traveled by each of them throughout the year astronomical . The nearest point of the planet from the star that followed called perigee (called Apsis in the solar system ) , while called the farthest point of the planet from the star followed by Apogee . When approaching the planet to the nearest point of the star, which increases the speed increases the influence of gravitational forces and weaken it kinetic energy , just as increasing the speed of a body fall to the ground . On the other hand , when it reaches the planet to the farthest point him for the planet , reduced speed, just as the fall speed of an object when it reaches the top of its trajectory when throwing it in the air to the top. [ 78 ] linked to describe the planet's orbit a range of elements and described as follows :
Decentralization: describe a decentralized orbit over the elongation of the planet's orbit . Valkwakb low decentralization , the orbits closer to the shape of the ring than in planetary high decentralization , where to take their orbits oval . [ 77 ] The objects in the Kuiper belt and the belt of comets (in addition to many planets outside the Total Solar ) high decentralization , and thus their orbits oval shaped to a large extent . [ 79 ] [ 80 ] 200 px an illustration of the semi-major axis Semi-major axis : it represents the distance between the planet and the halfway point, when the longest diameter of the oval orbit (see photo) . This distance will vary the distance where the planet at the farthest point from the star ; where it is impossible to be the star at the center of the planet's orbit . Tilt: tell us the degree of inclination of the planet is the extent to which orbit about the planet for a certain reference level . In the solar system , the reference level is the level of orbit of the planet Earth and the so-called solar orbit . As for planets outside the solar system , this level , known as the sky or the plane of the sky is the standard line of vision for the Monitor from above the ground .  There are eight planets own the solar system near the orbit of the solar , but located about objects in Kuiper belt and the belt of comets like Pluto dramatically . [82 ] called on the two points passes in which the planet above the reference level has its own beneath the name of the ascending node and the node downlink . [ 77 ] longitude of the ascending node is the angle between the node downside of the planet and longitude zero reference level . The nadir angle is the angle between the ascending node of the planet and its closest point to the star
Mi axis AxialTiltObliquity.pngEarth's axis inclination angle of 23 degrees inclination axis , they form an angle with the lines flush Alnujom own . This would change the amount of light connecting to each half of the planet throughout the year. When the northern hemisphere away from the star , the southern half in the face and vice versa . Thus, we say that each planet where the seasons are changing weather conditions throughout the year. And knows the time when half of the planet in the face of the star , or away from him as the " coup ." Each planet passes Pfterta coup over its orbit : a coup and a summer in which the day and the long winter and the coup in which the day is short . As well as , changes occur yearly in the weather on the planet according to the amount of light and heat hyphen for each half of it. Featuring mile Besgrh axis of Jupiter , and therefore does not occur significant seasonal changes . The Uranus , tends centered largely to the extent that it spins on its side , which means that half of it be dark or illuminating consistently during the summer solstice or the winter as a whole.  With respect to planets outside the solar system , the mile -centered unknown in sure , although it is known that hot Jupiters tend not centered at all or do not remember the degree tends approached a result of the stars that followed . 
Planets also revolve around the axis of its centers across fake . The period of the planet's rotation around its axis "Today" on this planet . And spin all the planets in the solar system in a counter-clockwise direction , with the exception of Uranus ; where spins in a clockwise direction [ 85 ] ( a planet orbits of Uranus in the counter-clockwise as well. [ 86 ] Given the tendency of its axis are very large , it can be said that he is going clockwise or reversible , it is possible to say that inclined at an angle 82 degrees from the orbit of the solar in one direction or say that inclined at an angle 98 degrees in the opposite direction ) . [ 87 ] this varies planets greatly in length on each of them , here it is: Venus takes on its axis about 243 Earth days , while not exceeding the duration of the session a few hours in the gas giant planets . [ 88 ] as well , is still a period of rotation of planets outside the solar system on its axis unknown . But the proximity to their stars means that hot Jupiters around its axis coincides with its host star about . This in turn means that the face and only one of them corresponds to the star , so the ones on the side of eternal day , while the other side is in perpetual night .  Evacuation orbital
Of kinetic properties characteristic of the planet that does vacate its orbit . It is intended that the orbital mass evacuation of the planet has increased enough to attract the embryonic planets located in the orbit or expelled outside . Vdoran planet in orbit around the star alone , of course, differs from the orbit to share this with many other objects, like his size. This has added this feature as part of the definition of the term " planet " which is the official definition adopted by the International Astronomical Union in August of 2006.  While this feature does not apply to the present day , but the solar system , there are a number of planets outside solar Group proved that the phenomenon occurs in tropical evacuation orbits disc format. [ 90 ] Physical characteristics Planet's mass
From the distinctive physical properties of the planets that mass large enough to overcome the forces of gravity in which the electromagnetic forces and help in the cohesion of the composition, including eventually lead to a state of hydrostatic equilibrium . This means that all the planets become spherical shape . This may take the form of an irregular planet when it reaches a certain amount of mass. But over that amount , gravity begins to pull the center of mass of the planet to the point that the balls form , note that it depends on its chemical composition .  Furthermore, it is the mass of the basic characteristics to distinguish between planets and stars . Reducing the maximum mass of the planet is to be twice the mass of Jupiter by 13 times, and if the mass above this value , so it will be an exhibition of occurrence of nuclear fusion . Generally , it is not in the solar luminary this entire block , with the exception of the sun, but there is a group of planets outside the solar mass of approaching this limit . It is worth mentioning that the list of Extrasolar Planets Encyclopedia contains many planets that up to this block , such as HD 38529c and AB Pictorisb and HD 162020b and HD 13189b. The encyclopedia also a number of celestial objects are high mass, but as long as the mass above the point of a nuclear fusion , then maybe you will be described more midgets structure. The smallest planet known to us , excluding dwarf planets and satellites is a planet PSR B1257 +12. This planet is one of the first planets that have been discovered outside the solar system has been discovered orbiting a star Tareq in 1992 . The mass of the planet half the mass of the planet Mercury approx. The difference in the internal structure Image shows the composition of Jupiter from the inside ; where consists of a rocky core covered with a thick layer of metallic hydrogen .
Each planet was a mass at the beginning. In the first stages of the configuration , accumulated heavy materials and the most densely at the center , leaving the lighter materials near the surface . Thus, we can say that each planet Internal Configuration different from the other materials containing heavy in his heart, surrounded by a layer of liquid or was a means in its infancy . Covering the rocky planets hard shell , [ 92 ] but for the gaseous giant planets cover melts in the upper layers of the sky . Well, the heart of the rocky planets consists of magnetic elements , such as iron , nickel and silicates . For Jupiter and Saturn , made up their heart of rock and metal surrounded by layers of metallic hydrogen . [ 93 ] On the other hand , consists heart planetary Uranus and Neptune and are smaller in size than the rocky core surrounded by layers of water , ammonia, methane and other ice. ] 94 ] it should be noted that the interaction between the fluid in the heart of the planets causes generate energy Jewdanamikih produce a magnetic field. Atmospheric 150 px atmosphere of the planet
All the planets in the solar system have an atmosphere as long as the force of gravity and which are attributable to the large mass large enough to keep gaseous particles near the surface. For the gas giants , are permitted to their large size to hold large quantities of light gases , such as hydrogen and helium near the surface , while the planets are small lose these gases into space. [ 95 ] as well , different atmospheric composition of the Earth from the other planets because the manifestations life on this planet has allowed the presence of free oxygen molecules . [ 96 ] and the only planet that has no atmosphere within the solar system is the planet Mercury because mostly faded , if not the whole by the solar wind . 
[ 97 ] A claim that a planet and one outside our solar system by the weather phenomena , such as the Great Red Spot , but the size of a multiplier , a planet HD 189733 b.  lose hot Jupiters atmosphere its own in space as a result of radiation asterisks , like the tails of comets . ] 99 ] [ 100 ] and these planets by substantial differences in temperature on the side of the day and by the night of them , produces winds of ultrasound , [ 101 ] this is despite the convergence temperatures significantly between both sides of the night and day on planet HD 189733b , which indicates that the atmosphere by the re- distribution of energy around the star very effectively . Magnetosphere Sketch for the cover of the Earth's magnetic
Of the important characteristics of the planets magnetic intention , which is why the emergence of magnetic covers . Vtkon magnetic field indicates that the planet is still geologically active . In other words , Valkwakb nature of magnetic flow inside electrically conductive materials , magnetic fields arise . These are areas that will change the pattern of interaction between the planet and the solar wind . And then , the planet's magnetic cavity work about the same in the solar wind can not penetrate the winds of the so-called " magnetosphere ." It is possible that this magnetosphere is larger than the planet itself . In contrast , non- magnetized planets casings produce small magnetic interaction between the ionosphere ( the ionosphere ) and the solar wind and can not protect the planet in any way .  In addition, the moon of Jupiter Ganymede has its own magnetic field . The magnetic field your planet Mercury is weaker magnetic fields at the level of planets with a magnetic field , and therefore , he can barely resist the solar wind . As for the magnetic field your moon Ganymede , is a strong significantly , however, the magnetic field of Jupiter, is the strongest of the magnetic fields in the solar system are all ( the magnetic field is very strong to the extent that it constitutes a real danger to the space flight future for humans to the moon ) . While the magnetic fields of gaseous giant planets are very much like other strength of the magnetic field of the Earth , but much larger than the magnetic nature . Well , skewed magnetic fields of the two planets Uranus and Neptune to the axis of rotation and left its place on the center of the planet .  In 2004, the monitoring team of astronomers in Hawaii extrasolar planets orbiting the star HD 179949 , leaving the spot Solar on the surface of its parent star . The team of scientists assumed that cover the planet's magnetic energy is transferred to the surface of the star , increasing the already high temperature of up to 14,000 degrees by 750 degrees.  Secondary characteristics
Many of the regular planets or dwarf planets in the Solar System ( such as Neptune and Pluto ) have orbital periods are compatible with each other or with other celestial bodies are smaller ( and this is common in systems Lunar ) . And all the planets except Mercury and Venus have natural satellites affiliates. The moon and the planet Earth and one of Mars and Qumran , the gas giant planets they have the many satellites that have a special system is complex . And co- own satellite giant gaseous planets with rocky planets and moons of dwarf planets in many features , some of which were also subject to study the possibility of a life of it (especially the " Europa " ) . Saturn's rings
Spin the four gas giants in planetary rings of different size and complexity. These rings are composed primarily of dust or the bodies of minutes , but it could accommodate small moons help to shape the forces of attraction and retention of those loops installed . Although the genesis of planetary rings is not known precisely , it is noteworthy that the origins are linked satellite natural located below the Roche planet's main bait forces trained and root . [ 104 ] [ 105 ] This was not monitoring any properties other secondary concerning extrasolar planets . ] 73