PLANETS OF OUR SOLAR SYSTEM

 

 New and old planets

            The 24 of August of 2006 Internacional Astronomical Union (IAU) in its XXVIº General Assembly in the Prague (Czech Republic) defined the terms planet, dwarf planet and small bodies of the Solar System and I more create the one of plutoniano after than two years working to define the new terminology due to the last discoveries of new bodies in our Solar System.

    Everything began in 2003 when the astronomers Michael Brown, Chad Trujillo, and David Rabinowitz discovered the 8 of January of 2005 from the Hard-twisted Mount observatory in the U.S.A. celestial body 200UB313 baptized by them as Xela but whose nomenclature not yet is official. When being more far than Pluto they classified them with asteroid that is in the ring of Kuiper but to the few months they discovered that its size is superior to the Pluto planet and therefore, were before the tenth planet of our discovered Solar System to date. With the passage of the months and thanks to the new and powerful telescopes they have been continued discovering perfectly definibles bodies of the Solar System like planets or asteroids.

    Before so many discoveries, a committee of wise people of the IAU been has reunited for more than two years to define the term planet and thus to make specific the number of them whom they orbit around our star, the Sun.

    Therefore, according to the IAU in his fifth resolution of XXVI the General Assembly it defined a planet like a celestial body that has a mass sufficient as to have its own gravity and forms rigid of such form that assumes a hydrostatic balance (next to the celestial sphere), that it orbits around a star not of a planet; in such case it would be a satellite and that it has cleared the environs of his orbit. The Nature will decide if an object is or not a planet.

    The definition is perfect since it defines it under very concrete characteristics so that a celestial object is defined as planet; first which the object must orbit around a star, second that must be the sufficiently great or massive thing (of mass) to have its own gravity and next to the spherical form or globe, therefore with a mass superior to 5x1020 kg and a diameter superior to 800 km, and third that is not accompanied in similiares orbits with other similar objects (this eliminates the asteroid belt like individual planets)

 

Planets of the Solar System

     The planets of our Solar System are in order to the distance to the Sun: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Urano and  Neptune.

 

    Therefore, with this perfect definition the planets of our Solar System in remote order of greater to minor are the following ones: Mercury, Venus, Earth, Mars, Jupiter, Saturn, Urano and Neptune. Other bodies Pluto, Charon and 200UB313. they become dwarf and plutonianos planets.

    The IAU defines to dwarf planets or asteroids like a celestial body that has a mass sufficient as to have its own gravity and forms rigid of such form that assumes a hydrostatic balance (next to the celestial sphere), that it orbits around a star not of a planet; in such case it would be a satellite and that it has not cleared the environs of his orbit and that it is not a satellite..

 

Planets of the Solar System

     The planets of our Solar System are in order to the distance to the Sun: Mercury, Venus, Earth, Mars,  Jupiter, Saturn, Urano  and Neptune. And the dwarf planets are: Ceres, Pluto, Charon and 200UB313.

 

   With this new definition the new dwarf planets that have been located to date of today are Ceres, Pluto, Charon and 200UB313.

   

   

The new dwarf planets of the Solar System

     According to the new planet definition approved in the General Assembly like a celestial body that has a sufficient mass as to have his own gravity and it forms rigid of such form that assumes a hydrostatic balance (next to the celestial sphere) and that it orbits around a star the new dwarf planets of our Solar System are: Ceres,   Pluto, Charon and 200UB313.

           

 

Plutonians

             We were with the planet definition and the creation of the plutoniano term to distinguish different types from dwarf planets or asteroids based on its diameter and orbital period.

    The IAU defines plutonian like the celestial object that fulfills the requirements of a dwarf planet with the written definition previously whose orbital period is superior to 200 years, is to say that it takes more than two centuries in giving a return around the Sun. An important characteristic of the plutonianos is that his it orbits moves away much of circulating therefore has a high eccentricity and inclination on the plane of the ecliptic of the Solar System. With this definition the origin of the plutonianos is different from the origin of classic planets of our Solar System.

    The plutonian name logically comes from Pluto,  prototype of this type of dwarf planets since it was first in being discovered, in 1930 and it is a spherical dwarf planet. Therefore, it is necessary to stand out that Pluto is a dwarf planet and in addition is plutoniano, but no longer is a planet of the Solar System.

    The plutonians planets of our Solar System are: Pluto, Charon and 200UB313.

 

Pluto and Charon

            Peculiarly as much Pluto as Charon is as there are saying previously plutonianos but in addition they orbit in the same distance of the Sun Has the particularitity that previously was considered to Charon as sátelite of Pluto but according to the last investigations the diameter of Charon is similar to the one of Pluto forming the new dwarf planet term double

            The IAU defines as binary dwarf planet like a pair of objects which independently  satisfy the dwarf planet definition and which they orbit one around the other through a point in common of a gravitational center denominated barycentre; whose barycentre in addition requires that it is not located inside anyone of the two celestial bodies or planets. That is to say, in our case as much Pluto as Charon both like planets are defined since they fulfill all the requirements for it but in addition when having similar diameters orbit around a fictitious point called barycentre that is neither within Pluto nor within Charon.

 

 

Pluto and Charon. Binary dwarf planet

    The photo is made by the space telescope Hubble, in her it is observed Pluto like the planet of the left and Charon like the one of the right. The size is similar and it is defined as dwarf planet since both fulfill a the dwarf Planet definition and in addition orbit in a barycentre outside the surface of both planets.

 

    In addition if we observed sitema of double planet of Pluto and Charon as it is observed in the image of the space telescope Hubble it deals with a formed Solar System by two satellites to date denominated Nix and Hydra.

 

The Solar System of Pluto and Charon

     The photo is made by the space telescope Hubble, in her it is observed the planets Pluto and Charon as well as their satellites having orbited these around the Pluto-Charon system.

Categories of the bodies of the Solar System

      The IAU classifies in three categories the celestial bodies of our Solar System in the following ones

  • First category: "a planet is a celestial body that is in orbit around the Sun, that has sufficient mass to have own gravity to surpass the rigid forces of a body so that assumes a balanced form hydrostatic, that is to say, round, and that has cleared the environs of its orbit".

  • Second category: "a dwarf planet is a celestial body that is in orbit around the Sun, that has sufficient mass to have own gravity to surpass the rigid forces of a body so that it assumes a balanced form hydrostatic, that is to say, round; that it has not cleared the environs of his orbit and that is not a satellite."

  • Third category: "All the other objects that they orbit around the Sun are considered collectively like ' small bodies of the Solar' System".

        The classic planets that are eight: Defined mercury, Venus, Earth, Mars, Jupiter, Saturn, Urano and Neptune like classic to the discovered ones from the Antiquity to year 1900.

        The dwarf planets defined as those whose diameter is inferior to the one of Mercury. In this Ceres case, that previously he was asteoride.

        And finally the plutonianos planets defined previously and that composes it, Pluto, Charon and 200UB313.

    Of this form the basic characteristicses of planets of our Solar System are as it follows:

Object Definition of the IAU Category IAU Category of description Diameter (Km) Distance A.U. Orbital period Date of location
Mercury Planet   Classic 4.879 0,387 88 days 07/Jun./1987
Venus Planet   Classic 12.104 0,722 225 days 00/Abr./1980
Earth Planet   Classic 12.746 1,00 365.25 days ----.
Mars Planet   Classic 6.780 1,53 687 days 00/Mar./1982 (Before the 18 of March)
Ceres Dwarf planet   Asteroid 952 2,77 4.60 years 03/Sep./1988
Jupiter Planet   Classic 138.346 5,20 11.86 years 00/Mar./1982 (Before the 18 of March)
Saturn Planet   Classic 114.632 9,54 29.46 years 00/Mar./1982 (Before the 18 of March)
Uranus Planet   Classic 50.532 19,20 84.01 years 14/Mayo/1983
Neptune Planet   Classic 49.105 30,09 164.79 years 23/Mayo/1987
Pluto Dwarf planet Plutonian

Plutonian

2.306±20 39,56 248.54 years Without locating.
Charon Dwarf planet Plutonian Plutonian 1.205±2 39,56 248.54 years Without locating.
200UB313 (provisional name) Dwarf planet Plutonian Plutonian 2.400 ±100 97 557 years Without locating.

 

Binary dwarf planet and satellites

    It is defined as binary dwarf planet that is the case in our Solar System of Pluto and Charon like a a pair of objects which independently satisfy the dwarf planet definition, but considers binary dwarf planet if both orbit one around the other and whose point or barycentre of both gravitational fields is outside the surface of some of them, in this case more near the Pluto surface but outside this planet.

        A satellite is therefore, a celestial body with sufficient mass as it defines the term planet and diameter but whose barycentre or center of gravity of both celestial bodies is within the surface of one of them call planet.

    Before this definition the system Earth  Moon cannot be considered like a double planet because the Moon fulfills the planet definition but it does not orbit around the Sun nor the barycentre of theTierra-Luna system is outside the planet Earth either. Thus like the Jupiter satellites (Io, Europe, Ganimedes or Calixto) whose conditions of planets fulfill it but whose barycentre is inside the gaseous Jupiter surface, al equal happens to Saturn and its satellite Titan.

    A dwarf planet is described like that planet whose diameter is smaller than the one of Mercury that is of 4879 km. It is not an official definition of IAU but a description of a type of planet is accepted rather in general but.

    What is Pluto. Before of the General Assembly of the IAU it was speculated on with the possibility of reducing the Pluto category like planet and of turning it asteroid, and thus it has been, Pluto passes to be a dwarf planet like Ceres and other bodies. In addition also we can reach the conclusion that Pluto is a dwarf planet by the definition consensuada by the IAU.

    The last photographies show the dwarf planet doubles to Pluto and Charon two new satellites that they orbit around them. Both do not consider planets because their size is inferior to 800Km, and do not have sufficient gravity to be spherical, therefore it is satellites and Pluto is not a quadruple planet.

    Quadruple or  triple planets can exist if the conditions for it are fulfilled, but in our Solar System this case does not occur. 

 

 Ceres

    Ceres is a dwarf planet. In 1801 when it was discovered Ceres historically it was defined as planet, but in century XIX the astronomers of the time could not calculate their diameter nor had idea of their form and as they were discovered several bodies the more between Mars and Jupiter were classified like asteroid and classified the zone like Asteroid Belt. Recent images of the space telescope Hubble have observed that is completely spherical and in addition it has terrestrial crust, but has not desepajado their orbit of other objects, therefore it continues being an asteroid but defined already like dwarf planet.

    Ceres also is a dwarf planet by its diameter but he is not plutoniano because its orbital period is not superior to 200 years. 

 

200UB313

    200UB313 is a dwarf planet because the last images of the space telescope Hubble demonstrate that it has a diameter superior to Pluto and in addition its form is spherical, is to say I balance hydrostatic, the name is provisional because it is the IAU that officially assigns the names of the celestial bodies. His discoverer gave the name him of Xena by a series of American fiction. Logically she is not official and it will be necessary to wait for months so that he has an own name that will be a God of Roman mythology.

    200UB313 is a plutoniano dwarf planet because its orbital period is superior to the 200 years and also dwarf because it has not cleared in its orbit other celestial objects séase Pluto, Charon, and other that will be continued discovering.

 

Dwarf candidates to planets

       In a next future they will continue themselves discovering more dwarf planets in our Solar System since we have more powerful and more precise telescopes. Candidates for new dwarf planets already exist but he has to be the IAU the one that decides the new list.

 

Objecto

Considered diameter nonofficial

2003the 61

2000×1000×1200 km

2005 FY9

1500±300 km

(90377) Sedna

1200-1800 km

(90482) Orcus

1000±200 km

(50000) Quaoar

~1000 km

(20000) Varuna

600 ± 150 km

(55636) 2002 TX300

< 700 km

(28978) Ixion

500±100 km

(55565) 2002 AW197

700±100 km

(4) Vesta

578×560×458 km

(2) Pallas

570×525×500 km

(10) Hygiea

500×400×350 km

  

             In the page Web you can obtain more data of each one of our ylos planets definidios dwarf planets by the IAU of our Solar System.

Masm © (Ultima actualización 20-oct-2006