Astronomy 70 - The Solar System - Terrestrial vs Jovian - Part 7

Overview

This lecture discusses the differences in the number of moons among the planets in our solar system, emphasizing key distinctions between terrestrial and Jovian planets.

Moons of the Inner Planets

• Mercury has zero moons.
• Venus also has zero moons.
• Earth has one moon.
• Many students mistakenly think Venus has a moon, but it does not.
• Mars has two moons.

Moons of the Outer Planets (Jovian Planets)

• Jupiter has a large, uncertain number of moons (at least 68 confirmed, more are often discovered).
• Saturn has at least 50 moons.
• Uranus has at least 20 moons.
• Neptune has at least 10 moons known, with the potential for more.
• Outer planets (Jovian) have many moons, while inner planets (terrestrial) have few or none.

Difficulty in Counting Moons

• The exact number of moons around outer planets is uncertain because they are far away.
• Many moons of Jovian planets are small and harder to detect.
• As planets are farther from Earth, it becomes more challenging to find and confirm their moons.

Key Terms & Definitions

• Terrestrial Planets — Mercury, Venus, Earth, and Mars; rocky planets with few or no moons.
• Jovian Planets — Jupiter, Saturn, Uranus, Neptune; gas giants with many moons.
• Moon (Natural Satellite) — A celestial body that orbits a planet.

Action Items / Next Steps

• Review the list of major moons for each planet.
• Prepare for exam questions about which planet has a certain number of moons.
• Remember: Earth is the planet with one moon.