In this Grade 6 Earth Science lesson from Chapter 21, students learn about the terrestrial planets — Mercury, Venus, Earth, and Mars — and how four key processes, including tectonics and volcanism, shape the surfaces of these rocky worlds. Students also explore how atmospheres form and influence planetary conditions, and why terrestrial planets share similar rocky crusts, dense mantles, and cores. The lesson uses Earth as a model to help students compare and understand the other inner planets closest to the Sun.
Section 1
Four Processes Shape Terrestrial Planets
Tectonics, volcanism, weathering/erosion, and impact cratering reshape rocky surfaces. Each process creates distinct features that provide evidence of a planet's geological history and internal activity.
Section 2
Volcanoes Release Gases to Form Atmospheres
Planetary atmospheres primarily form when volcanic eruptions release gases. A planet's gravity must be strong enough to retain these gases, which can then regulate temperature and transport energy across the surface.
Section 3
Planets Separate Materials to Form Layers
When planets form, heat from collisions melts materials. Dense metals sink to create cores, while lighter rocks rise to form crusts, creating distinct layers based on density differences.
Section 4
Mars Shows Evidence of Ancient Water
While Mars currently has no liquid water, landforms suggest massive floods occurred in its past. Today, water exists only as ice in polar caps and underground, with winds causing erosion instead.
Section 5
Venus Traps Heat Through Greenhouse Effect
Venus's dense carbon dioxide atmosphere traps heat, creating surface temperatures of 470°C. Despite rotating slowly with two-month days, the thick atmosphere distributes heat evenly across the planet.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter
Expand to review the lesson summary and core properties.
Section 1
Four Processes Shape Terrestrial Planets
Tectonics, volcanism, weathering/erosion, and impact cratering reshape rocky surfaces. Each process creates distinct features that provide evidence of a planet's geological history and internal activity.
Section 2
Volcanoes Release Gases to Form Atmospheres
Planetary atmospheres primarily form when volcanic eruptions release gases. A planet's gravity must be strong enough to retain these gases, which can then regulate temperature and transport energy across the surface.
Section 3
Planets Separate Materials to Form Layers
When planets form, heat from collisions melts materials. Dense metals sink to create cores, while lighter rocks rise to form crusts, creating distinct layers based on density differences.
Section 4
Mars Shows Evidence of Ancient Water
While Mars currently has no liquid water, landforms suggest massive floods occurred in its past. Today, water exists only as ice in polar caps and underground, with winds causing erosion instead.
Section 5
Venus Traps Heat Through Greenhouse Effect
Venus's dense carbon dioxide atmosphere traps heat, creating surface temperatures of 470°C. Despite rotating slowly with two-month days, the thick atmosphere distributes heat evenly across the planet.
Book overview
Jump across lessons in the current chapter without opening the full course modal.
Continue this chapter