Owing to the classification of Pluto as one of the dwarf planets by IAU, the eight planet -solar system is categorized into two domains; Terrestrial and Jovian planets. These two domains are distinct in the uniqueness of their characteristic features. Terrestrial planets comprise of Mercury, Venus, Earth and Mars, they are near the proximity of the Sun to their Jovian counterparts which include; Jupiter, Saturn, Uranus and Neptune. It is interesting to note that, though the Jovian planets are further away from the sun than the Terrestrial planets, the speed with which they spin on their own axis is relatively higher.
Apart from the relative positions of the Jovian and Terrestrial planets from the sun, another striking difference between them is in their relative masses and sizes. Whereas the Jovian is gigantic and massive the terrestrial planets are relatively smaller in size and less massive. For instance, the Earth which is the largest of the terrestrial planets is one-tenth the size of the smallest Jovian planet, whose mass is fifteen times that of the earth. Surprisingly though is the ironic comparison of the relative densities of the Jovian and Terrestrial planets, with the densities of the Jovian planets being relatively lower than those of the terrestrial planets.
The other front of distinct features evident in the Jovian and the Terrestrial planets is in their composition. Whereas the outer surface of terrestrial planets basically comprises solid rocks that of the Jovian planets are gaseous. In addition to this, although a greater percentage of the terrestrial planets’ atmosphere comprises nitrogen and carbon dioxide gases that of the Jovian planets constitute hydrogen and helium.
The other notable distinctive feature between the Jovian and Terrestrial planets is the number of satellites, with Jovian planets having several or large numbers of satellites and the Terrestrial planets having few or none.
Classification of Smaller Bodies in the Solar System
Smaller bodies than the planets, but relatively larger than the satellites, in the solar system are broadly classified as either asteroids or comets. Asteroids are small and rocky non-atmospheric bodies that orbit the sun, many of them are gathered in the asteroid ring sandwiched between Mars and Jupiter. Comets are space snowballs of dust, rock, and frozen gases, when close to the sun; it heats up and assumes a gigantic glowing head with the dust and gases forming a tail that extends some millions of kilometers from the sun.
Of particular feature, are the meteors and meteorites. Meteoroids are little pieces of rocks and debris in space. Meteors fall in space and being heated to incandescence by atmospheric friction leave a bright trail.
Explanation of Pluto
The disqualification of Pluto as one of the nine planets of the solar system was triggered by the discovery of a Kupler Belt Object orbiting the sun-which was relatively larger than Pluto in the July of 2005 by a team of astronomers. The object – later given the name Eris also had a small satellite called Dysnomia. This compelled the International Astronomical Union to either; consider including Eris as the tenth planet or form a new class of objects (dwarf planets). The latter option prevailed and saw the creation of dwarf planets of which Pluto is part.
Kuiper Belt
The Kuiper Belt is a disc-shaped region just beyond Neptune believed to harbor short–period comets; it is at the same plane with most planetary orbits in the solar system.
Oort cloud
The Oort cloud surrounds the solar system, it is thought to be at the region where the sun’s gravitational power ends.