Overview
This lecture explains the classification of planets in our solar system, their shared characteristics, and key differences between terrestrial and Jovian planets.
Types of Planets
- The four outer planets (Jupiter, Saturn, Uranus, Neptune) are called Jovian planets, meaning "Jupiter-like."
- The four inner planets (Mercury, Venus, Earth, Mars) are called terrestrial planets, meaning "Earth-like."
- Earth is the model for terrestrial planets, Jupiter is the model for Jovian planets.
Shared Characteristics of All Planets
- All planets orbit the Sun.
- All planets are round in shape.
- Each planet follows an elliptical (oval) orbit.
- All planets orbit in the same direction.
- The orbits of the planets are roughly in the same plane, making the solar system "flat."
- The reasons for these similarities relate to how the solar system formed.
Major Differences: Terrestrial vs. Jovian Planets
- Terrestrial planets have small orbits (closer to the Sun); Jovian planets have large orbits (farther from the Sun).
- Terrestrial planets are smaller in size; Jovian planets are much larger.
- Jupiter is the largest planet; Mercury is the smallest planet.
- Some moons are larger than Mercury, but only objects orbiting the Sun directly are considered planets.
- Jovian planets have rings; terrestrial planets have no rings.
Key Terms & Definitions
- Terrestrial planets — planets that are Earth-like, including Mercury, Venus, Earth, and Mars.
- Jovian planets — planets that are Jupiter-like, including Jupiter, Saturn, Uranus, and Neptune.
- Orbit — the path a planet follows around the Sun, typically elliptical in shape.
- Plane — the nearly flat disk in which planets orbit the Sun.
Action Items / Next Steps
- Prepare to discuss why Pluto is no longer classified as a planet (upcoming lecture).
- Make sure there is enough space for more differences between terrestrial and Jovian planets in your notes.