Rocky planets are formed when the deepest parts of the rock are warm. The planet's sun or protostar making the heavier elements sink to the deepest parts and stay there by warming the planet.
The basic answer is that planets that are mainly gas could not survive close to the Sun. The temperature would cause the gas to escape into space.
All planets are formed form the remains of the solar nebular.
The inner planets are rocky and solid because they formed closer to the sun where it was too hot for volatile gases to condense. The outer planets formed in colder regions where volatile gases like hydrogen and helium could condense, leading to their gaseous composition and icy centers.
Mercury is a rocky planet. The inner planets (first four planets from the sun) are rocky planets (which means that you could stand on them) and are the smallest. While the outer planets (last four planets from the sun) are gas planets and the biggest.
Rocky planets and gaseous planets.
The current explanation is that while the planets were forming the solar winds tended to push gaseous substances further out toward the rim of the 'accretion disk' of pre-planetary materials, leaving the rock behind. Even the gas giants have cores of rocky or metallic composition, although their bulk is overwhelmingly the gases that came together around them.
By "accretion" of "planetesimals" from the "protoplanetary disk".
the sun was bigger and brghter then gave birth to four gas planets then rocky ones and probable give birth again our system is getting larger the planets lining up just might do that 26000 104000 104000000 anamate solar system in reverse its possibe
All planets are formed form the remains of the solar nebular.
Rocky planets
The inner planets are all considered rocky planets in that under atmospheric layers, they have a rocky surface. The outer planets are made of gas and liquid, and are called gas giants. They have no solid surface. Also, all the outer planets have rings while the inner planets do not.
Th inner planets are rocky because as the Sun and planets formed the more volatile elements could not condense into droplets near to the hot Sun. Thus the inner planets are made form stuff with a high melting/boiling point and the outer planets (where it was cooler) are made from the gases.
Terrestrial Planets, or Rocky Planets.
the gas planets are bigger than the rocky planets
Pieces of rocks made of minerals similar to those that are formed the rocky planets and moons.
There are four rocky planets in the solar system: Mercury, Venus, Earth, and Mars.
rocky
they are rocky and have terrain areas the rest of the planets are all gas