Planet
From Aetilc
Planet [Gr.,wanderer], a large non-luminous body of rock or gas that orbits a star, has a rounded shape due to gravity, and has cleared its orbit of smaller objects. The term planet sometimes has been used to include dwarf planets and asteroids (or minor planets); it does not include comets and meteoroids.
On the basis of their physical properties the planets are further classified as terrestrial or Jovian. The terrestrial planets resemble Earth in size, chemical composition, and density. Their periods of rotation range from about a few hours to several days. The Jovian planets are much larger in size and have thick, gaseous atmospheres and low densities. Their periods of rotation range from about 10 hours to 15 hours. This rapid rotation results in polar flattening of 2% to 10%, giving the planets an elliptical appearance.
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[edit] Terrestrial Planet
Terrestrial planet is a planet that resembles the earth in its physical characteristics. These planets are approximately the same size ranging from 2,000 to 15,000 km in radius. They are considerably denser than the Jovian planets, ranging from a specific gravity from 4 for Mars to 5.5 for the earth. Because they spin less rapidly than the Jovian planets, the terrestrial planets are less flattened at their poles.
[edit] Jovian Planet
Jovian planet, are larger and more massive than terrestrial planets. Since they rotate faster, they are more flattened at the poles than are the terrestrial planets. They are less dense than terrestrial planets, as they are composed of gaseous matter, predominantly hydrogen.
