As its name implies, the solar system is driven by the energy of the Sun. Its size is trillions of miles wide, covering eight planets with their satellites and an incalculable number of asteroids, comets and meteoroids. The Nebular Theory aims to explain how it all started and how it got its actual shape. It states that the Sun and planets formed from a rotating cloud of interstellar gases and dust named the solar nebula. Because of the gravity, the contraction of the solar nebula caused the majority of materials collected in the center to form the hot protosun and the rest to form a thick rotating disk, within which matter gradually cooled and condensed into grains of icy and rocky material. Repetition of collisions caused the collection of materials into planetesimals, objects approximately as big as asteroids and with a different composition each depending on their proximity to the sun. Because of this proximity with the protosun, planetesimals present between the orbits of Mercury and Mars were mainly formed of materials with high melting temperatures, and by several collisions and accretions, they combined and formed the four protoplanets that we know today as Mercury, Venus, Earth and Mars. The planets of the solar system are divided into 2 different categories (Terrestrial or inner planets: Mercury, Venus, Earth, Mars and Jovial or outer planets: Jupiter, Saturn, Uranus, Neptune) depending on their location, size, and density. A new class of solar system bodies called dwarf planets has been identified and that’s where objects like Pluto belong. Scientists estimate that approximately 99.85% of solar system’s mass is contained within the Sun, and the planets represent the majority of the resting 0.15%.