Medium-sized Moons

Definition: Medium-sized moons are celestial bodies ranging from 200 to 800 kilometers in radius (400 to 1,600 km in diameter).
Composition: Primarily composed of rock or ice (water).
Orbital Characteristics:
- Circular orbits around their respective planets.
- Mostly tidally locked, presenting the same face to the planet at all times (similar to Earth's Moon).
Appearance: Heavily cratered surfaces indicating age and limited geological activity.

Total Number: 12 medium-sized moons found across planets.
Breakdown by Planet:
- Saturn: 6 moons
- Uranus: 5 moons
- Neptune: 1 moon.
Data Representation:
- Orbital period is similar to an Earth day.
- Mass is compared relative to Earth's Moon.
- Largest medium-sized moon is about 5% the mass of Earth's Moon.

General Characteristics: Most moons appear dark or gray with a few brighter exceptions.
Key Moons of Saturn:
- Rhea and Dione:
  - Light wispy terrain, potential water involvement.
  - Features icy cliffs formed from tectonic fractures.
  - Icy volcanism in Dione similar to lunar maria but made of ice.
- Mimas:
  - Contains a large impact crater relative to its size, nicknamed the "Death Star".
- Tethys:
  - Exhibits numerous surface cracks potentially from impact and volcanic activity.
- Iapetus:
  - Unique structure with one bright and one dark hemisphere.
  - Features a large ridge (20 km tall) that spans half the moon (1,400 km long).
- Enceladus:
  - Evidence of geologic activity; surfaces are mostly ice-covered.
  - Reflects nearly 100% sunlight, indicating a highly reflective ice surface.
  - Possible presence of an atmosphere composed of water vapor; geologic activity includes ice-volcanism that ejects ice ash.