The main reason that the inner planets are much more rocky and the outer planets are gaseous has to do with the condensation of materials. When the Solar System was being formed according to the "Solar Nebula Hypothesis", the Solar System began as a rotating disk of gas and dust. The majority of this material formed the Sun, and the rest of it was left to form the planets. The material closest to the Sun was obviously the hottest, and therefore any lighter materials such as gases would have evaporated and been vaporized by the Sun's heat. The materials with a higher melting/condensing point, such as iron, nickel, and other rock-forming substances could remain solid at these higher temperatures and therefore eventually accreted (came together) to form the inner, or Terrestrial planets. The materials with lower condensing points, gases such as methane, ammonia, water etc, were able to condense out further from the Sun where it was cooler and accreted into the gas giants we have in the outer part of the Solar System called the Jovian planets. It is believed that the Jovian planets started with large "seeds" of solid material made of up of rock and ices, and then their gravity attracted all of the gas in the region. This will unfortunately have to remain a theory as we would never be able to visit the centers of the Jovian planets due to the tremendous pressures that exist there.
Reference:
Freedman, R. A., Geller, R. M., and Kaufmann, W. J. 2008, Universe (9th Ed.; New York, NY: W. H. Freeman and Company)
the inner planets are rocky and warm and the outer planets are made out of gas and is cold
the outer planets are gaseous and the inner planets are not
Inner planets small and rocky. Outer planets big and gassy.
Because the inner planets are made of rock but the outer planets are made of gas(except for Pluto).
the inner planets are made of rock, ice and other materials while the outer planets are made of different kinds of gases except for pluto.
Inner planets. are inner & outer planets. are outer
the inner planets are rocky and warm and the outer planets are made out of gas and is cold
the inner planets are rocky and warm and the outer planets are made out of gas and is cold
the outer planets are gaseous and the inner planets are not
Inner planets small and rocky. Outer planets big and gassy.
The inner planets are all rocky planets. The outer planets are completely made up of gases. The inner planets are much smaller than the outer planets.
The inner planets are hotter because they are the closest to the sun the outer planets are the coldest because they are the farthest planets from the sun
Because the inner planets are made of rock but the outer planets are made of gas(except for Pluto).
the inner planets are made of rock, ice and other materials while the outer planets are made of different kinds of gases except for pluto.
The inner planets are small and rocky, the outer planets are much larger and have no solid surface, they are called the gas giants.
inner=terrestrial outer=non terrestrial
the inner planets are closest to the sun and the outer planets are farthest from the sun { Answered by a grade 4 student}