Planets of the Solar System / Los Planetas del Sistema Solar

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A planet is an astronomical object orbiting a star (the Sun in our Solar system) or stellar remnant  that is massive enough to be rounded by its own gravity. The planets in our system might be divided in three groups according to the IAU definition of planet of 2006:

- Inner terrestial rocky planets: Mercury, Venus, Earth and Mars.
- Outer gas giant Planets: Jupiter, Saturn, Uranus and Neptune. 
- Dwarf planets: Ceres, Pluto, Eris, Makemake and Haumea.

According to the IAU resolution, the definition of planet in the Solar System set in 2006 states that a planet is a celestial body which:
  • is in orbit around the Sun,
  • has sufficient mass to assume hydrostatic equilibrium (a nearly round shape)
  • is not a satellite of a planet or any other stellar body.
There is a forth rule, much discussed, that sets a difference between dwarf planets and the classical ones:
  • has "cleared the neighbourhood" around its orbit.
Bodies which fulfill the first two conditions but not the third were classified as dwarf planets, provided they are not also natural satellites of other planets.

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Los planetas son aquellos que orbitan alrededor de una estrella, en nuestro caso, el Sol. Podríamos dividirlos en tres grupos según establecida por la resolución 5A de la Unión Astronómica Internacional (UAI): 

-Terrestres, Rocosos o Interiores: Mercurio, Venus, la Tierra y Marte
-Gaseosos, Gigantes o Exteriores: Júpiter, Saturno, Urano y Neptuno
-Planetas enanos: Ceres; y los llamados plutinos: Plutón, Eris, Makemake y Haumea.

Según dicha resolución, un planeta es un cuerpo celeste que:

  • Está en órbita alrededor del Sol.
  • Tiene suficiente masa para que su propia gravedad haya superado la fuerza de cuerpo rígido, de manera tengan un equilibrio hidrostático (forma casi esférica).
  • No es un satélite de un planeta u otro cuerpo no estelar.
Además hay una cuarta regla, muy discutida, que diferencia a los planetas “clásicos” de los planetas “enanos”, ya que no es cumplida por estos últimos:
  • Han limpiado la vecindad de su órbita.
Además también giran alrededor del sol un conjunto de otros cuerpos tales como asteroides, satélites naturales, cometas, etc.

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Solar System in English

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