Lesson 2: Planetary Formation and Differentiation
Duration of Days: 10
Lesson Objective
Students will be able to analyze how planets form through accretion of planetesimals, evaluate how mass, temperature, and composition determine whether a planet becomes terrestrial or a gas/ice giant, and use density and compositional data to explain planetary differentiation and internal structure.
-How do variations in temperature and material availability in the protoplanetary disk influence planet formation?
-Why do rocky planets form closer to the Sun while gas and ice giants form farther away?
-How does gravitational energy and radioactive decay drive planetary differentiation?
-What evidence from planetary density and composition data supports models of internal layering?
-How do exoplanet discoveries challenge or refine our understanding of planetary formation?
Planetesimal
Accretion
Protoplanet
Terrestrial planet
Gas giant
Ice giant
Differentiation
Core, mantle, crust
Volatiles
Density
Orbital migration
HS-ESS1-2 – Use models and observational evidence to explain the formation and internal structure of planets.
NGSS Crosscutting Concepts
-Cause and Effect
-Systems and System Models
-Patterns
-Energy and Matter
Students will interpret planetary density, mass, and radius data to identify compositional differences
Students will analyze graphs comparing terrestrial and gas/ice giant planets
Students will construct evidence-based explanations using real planetary datasets
Students will investigate how planets grow from planetesimals through repeated collisions and gravitational attraction. They will analyze how heat from impacts and radioactive decay causes planetary interiors to separate into layers. Students will compare solar system planets and selected exoplanets to identify patterns in composition, density, and formation location.
Students will use data analysis and modeling to explain how different environmental conditions in the early solar system produce distinct planet types.
Activities May Include
Modeling accretion and collision processes using physical or digital simulations
Analyzing density vs. composition data for planets in and outside our solar system
Constructing layered internal structure diagrams based on evidence
Comparing exoplanet and solar system planetary systems
Purpose
Develop students’ ability to interpret multi-variable planetary data sets and connect formation conditions to long-term planetary structure and classification.
DOK Level
DOK 4 – Extended Thinking
(Requires multi-step reasoning, comparative analysis, and data-driven modeling of planetary systems)
Students connect planetary formation research to NASA missions such as Juno, Cassini, Mars rovers, and ongoing exoplanet discovery missions that are reshaping how scientists understand planetary diversity across the galaxy.
-Students may think planet formation is uniform across all systems
-Students may believe size alone determines planet type
-Students may confuse density with mass or composition
-Students may not understand differentiation as a heat-driven internal process
Dual-level planetary data interpretation (basic vs advanced datasets)
Step-by-step scaffolds for interpreting density and composition graphs
Visual supports for internal structure modeling
Extension: exoplanet comparison analysis using real mission data
- Planet classification using data tables
- Constructed-response explanations using evidence
- Internal structure diagram evaluation
- Simulation-based modeling tasks
- Planetary mass, radius, and density datasets
- Accretion and differentiation simulations
- NASA planetary mission data (Juno, Cassini, Mars rovers)
- Exoplanet comparison visuals and datasets