Differentiation, in the context of planets, means a. comparing a planet to others to better understand its features. b. that different parts of the planet have different compositions. c. that different planets have different compositions. d. calculating the slope of the trajectory.

The composition of planets is vital to understand their structure and behavior. Planetary composition refers to the variety of materials that make up a planet. These materials include gases, liquids, and solids. Different planets have distinct compositions based on their proximity to the Sun and their formation processes.
For instance, terrestrial planets like Earth and Mars are rich in silicate rocks and metals, especially iron. Gas giants like Jupiter and Saturn are composed largely of hydrogen and helium, with possible cores of rock and metal.

• Earth’s composition includes elements like iron (Fe), oxygen (O₂), silicon (Si), and magnesium (Mg).
• Mars has a similar composition to Earth but with a higher concentration of iron oxide, giving it a red appearance.
• Jupiter’s composition is dominated by hydrogen (H₂) and helium (He), with elements like methane (CH₄) and ammonia (NH₃) in smaller amounts.

Understanding the composition helps scientists learn about the origin and evolution of each planet, and it also informs how planets may support various forms of life.

The structure of a planet defines how its interior is organized. Planets typically have several layers, with each layer made up of different materials. These layers vary significantly between terrestrial planets and gas giants.
Terrestrial planets, such as Earth, have a layered structure consisting of:

• Crust: The outermost shell, composed mainly of silicate rocks.
• Mantle: A thick layer of silicate minerals rich in iron and magnesium, which is semi-fluid and flows slowly.
• Core: The innermost layer, primarily composed of iron and nickel, divided into a solid inner core and a liquid outer core.

Gas giants, like Jupiter, have a more complex structure with:

• Atmosphere: Thick layers of hydrogen and helium gas.
• Metallic Hydrogen Layer: Hydrogen in a metallic state due to immense pressure.
• Core: A possible rocky and metallic center, surrounded by layers of ice and rock under extreme pressure.

Studying planetary structure helps scientists understand the geological processes that shape a planet, its magnetic field, and even its ability to support life.

Planets undergo several internal processes that influence their development and current state. These processes can include differentiation, convection, and plate tectonics.
Differentiation is a process in which a planet's material separates into different layers based on density. Heavier materials like iron sink to form the core, while lighter materials rise to form the crust.
Convection occurs mainly in the mantle of terrestrial planets and involves the movement of heated materials. As material heats up, it becomes less dense and rises towards the surface. When it cools, it sinks back down.
Plate tectonics is specific to Earth and involves the movement of large plates on the planet's surface. These plates slowly move due to convective currents in the mantle, leading to the formation of mountains, earthquakes, and volcanic activity.

• Volcanism: Occurs when magma from the mantle reaches the surface, forming volcanoes and new crust.
• Magnetism: Generated by the movement of conductive materials in the core, creating a planet's magnetic field.

These internal processes are crucial for maintaining a planet's surface and atmosphere and can influence the potential habitability of a planet.