Gravity pulled materials together forming the planets in our solar system. The inner planets consist of dense material, such as iron, which was pulled to the center of the planets. Materials such as ice. liquid and gas formed the outer planets. Scientist identify this process as: Planetary Arrangement Solar System Systematic Development Planet Differentiation Heavy Metal Gaseous Planetary Design

The inner planets are composed of cooled igneous rock with iron cores, which are geologically active. The scientist identify this process as Planetary differentiation.

Gravity is known to holds the planets in orbit around the sun and what keeps the moon in orbit around Earth. The gravitational pull of the moon also pulls the seas towards it, leading to ocean tides.

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B. Solar System Systematic Development.

Explanation:

Solar system systematic development can be defined as a systematic monitoring, evaluation and study of the differences and similarities among the planets (earth, mars, jupiter, neptune, uranus, mercury, pluto, saturn and venus), as well as obtaining a deeper insight into how the solar system and other planetary bodies  were formed and have evolved over time.

This has helped scientists to understand that, gravity pulled materials (low-density cloud of interstellar gas and dust known as a nebula) together forming the planets in our solar system. The force by which planetary bodies pull objects equally from all sides toward its center is known as gravity.

Basically, the inner planets are relatively small in size and are made up of rocks. The inner planets includes earth, venus, mercury which are closest to the sun. The outer planets are relatively larger in size and are composed of gases. The outer planets includes saturn, jupiter, neptune and uranus which are further away from the sun.

The inner planets consist of dense material, such as iron, which was pulled to the center of the planets while materials such as ice, liquid and gas formed the outer planets.