Unlike the giant planets, the terrestrial planets formed when a. the inner Solar System was richer in heavy elements than the outer Solar System. b. the inner Solar System was hotter than the outer Solar System. c. the outer Solar System took up more volume than the inner Solar System, so there was more material to form planets. d. the inner Solar System was moving faster than the outer Solar System.

Planet formation is a fascinating process that began shortly after the Sun formed. The Solar System started from a giant cloud of gas and dust. Over time, this material collapsed under gravity, forming a spinning disk called the solar nebula.
The center of this nebula became the Sun, while the rest of the material started to clump together, forming planetesimals.

Planetesimals are small celestial bodies that became the building blocks of planets. As these planetesimals collided and stuck together, they formed larger bodies known as protoplanets. The type of planet that formed depended on the distance from the Sun and the materials present.

The inner Solar System, being closer to the Sun, was very hot. Due to these high temperatures, only materials with high melting points, such as metal and rock, could survive. This is why terrestrial planets, like Earth and Mars, are mostly composed of these substances. In contrast, the outer Solar System was cooler, allowing ices and gases to remain solid. Hence, the giant planets, like Jupiter and Saturn, formed with significant amounts of these lighter materials.

Terrestrial planets, also known as rocky planets, are primarily composed of metals and silicate rocks. The key features that distinguish terrestrial planets from other types of planets are their solid surfaces and smaller sizes.

The four terrestrial planets in our Solar System are Mercury, Venus, Earth, and Mars. These planets have common characteristics:

• High density due to metallic and rocky compositions
• Thin to no atmospheres
• Relatively small sizes and masses

The formation of terrestrial planets is closely tied to the conditions in the inner Solar System. Being closer to the Sun, these regions were hotter. This high temperature caused volatile compounds, like water and methane, to evaporate. Thus, terrestrial planets generally lack the thick atmospheres and icy compositions seen in the outer planets.

Over millions of years, planetesimals in the inner Solar System collided and merged to form the terrestrial planets we see today. The intense heat from these collisions and from the young Sun caused further differentiation within these planets, leading to their distinct layered structures with dense metallic cores and rocky mantles and crusts.

The inner Solar System is the region of space that encompasses the four terrestrial planets: Mercury, Venus, Earth, and Mars. This area extends up to the asteroid belt, which lies between Mars and Jupiter.

One of the defining characteristics of the inner Solar System is its relative proximity to the Sun. As a result, it experiences much higher temperatures compared to the outer Solar System. This heat influences the types of materials that could condense and form solid bodies.

Unlike the outer Solar System, which has gas giants like Jupiter and Saturn, the inner Solar System is dominated by rocky bodies. Here are some key conditions of the inner Solar System that shaped planet formation:

• High temperatures due to proximity to the Sun
• Rich in heavy elements like iron and silicon
• Lower availability of light gases and ices

The intense solar radiation and heat helped to clear out lighter elements and gases, leaving behind denser materials. This created an environment ideal for forming the smaller, rockier terrestrial planets. Over time, as the inner Solar System cooled, the solid materials accreted into planetesimals and eventually into the terrestrial planets we see today. The unique conditions of the inner Solar System were essential in shaping the characteristics and development of these rocky worlds.