Overview
This lecture explains the composition and structure of Jovian (gas giant) planets, comparing them with terrestrial planets like Earth and emphasizing why Jovian planets are not considered "mostly solid."
Structure of Jovian Planets
- Jovian planets, also called gas giants, are not mostly solid.
- Each Jovian planet has a solid rocky core made of rock and metal, similar to terrestrial planets.
- The solid core is located at the center because solid materials are denser and sink inward due to gravity.
- Despite their name, Jovian planets can contain more solid material than Earth.
Composition Comparison: Jovian vs. Terrestrial Planets
- Earth is considered "mostly solid" because solids make up the majority of its volume.
- Jovian planets have so much more gas and liquid compared to their solid core that they are not considered "mostly solid."
- The enormous quantity of gas and liquid in Jovian planets overshadows the presence of solids.
Oceans on Earth and Jupiter
- Earth's ocean is extremely thin compared to Earth's diameter; it is a tiny fraction of the planet's width.
- Jupiter has an “ocean” that is thousands of times deeper than Earth's, potentially deep enough to fit multiple Earths stacked on top of each other.
- Jupiter’s ocean is not made of water but is composed of liquid hydrogen and helium.
Key Terms & Definitions
- Jovian planets — Large planets, primarily composed of gas and liquids, including Jupiter, Saturn, Uranus, and Neptune.
- Gas giants — Another term for Jovian planets, emphasizing their gaseous composition.
- Rocky core — The dense, solid center of Jovian planets made of rock and metal.
- Terrestrial planets — Planets like Earth, primarily composed of solid rock and metal.
- Hydrogen and Helium — The most abundant elements in Jovian planets, making up their vast liquid and gaseous layers.
Action Items / Next Steps
- Review the structure and composition of Jovian versus terrestrial planets.
- Prepare to discuss how scientists know the composition of planetary cores in upcoming lessons.