Callisto

Definition

Callisto is the second-largest moon of Jupiter and the third-largest moon in the Solar System. It is the fourth-largest moon overall and the largest of the Galilean moons. Callisto's composition is similar to that of the other Galilean moons, consisting of approximately equal amounts of rock and ice, making it one of the most heavily cratered objects in the Solar System.

5 Must Know Facts For Your Next Test

1. Callisto has a heavily cratered surface, indicating that it has been geologically inactive for billions of years, unlike its sibling moons Io and Europa.
2. Callisto's surface is composed of a mixture of water ice and silicate rock, with a subsurface ocean believed to exist beneath its icy crust.
3. Callisto's orbit around Jupiter is the most distant of the four Galilean moons, with a semi-major axis of approximately 1.88 million km.
4. The low density of Callisto suggests that it has a relatively large amount of ice in its composition, with a rock-to-ice ratio of approximately 1:1.
5. Callisto's lack of significant internal heating and geological activity is thought to be due to its distance from Jupiter, which reduces the tidal forces exerted on the moon.

Review Questions

• Explain how the composition and geological characteristics of Callisto relate to its formation and evolution within the Jovian system.
  • Callisto's composition, consisting of roughly equal parts rock and ice, and its heavily cratered surface indicate that it has been geologically inactive for a significant period of time. This is likely due to its distance from Jupiter, which reduces the tidal forces exerted on the moon, limiting internal heating and geological activity. The low density of Callisto suggests that it has a large amount of ice in its composition, which is a result of the moon's formation and evolution within the Jovian system.
• Describe the role of orbital resonance in the dynamics and evolution of the Galilean moon system, including Callisto.
  • The Galilean moons, including Callisto, exhibit a phenomenon known as orbital resonance, where their orbits become synchronized due to the regular, periodic gravitational influence they exert on each other. This orbital resonance plays a significant role in the dynamics and evolution of the Galilean moon system, affecting factors such as tidal heating, orbital stability, and the overall structure and evolution of the system. Understanding the orbital resonance between Callisto and the other Galilean moons is crucial for understanding the complex dynamics of the Jovian system.
• Analyze how the distance of Callisto from Jupiter, compared to the other Galilean moons, impacts the moon's internal structure, surface features, and overall evolution.
  • Callisto's distance from Jupiter, being the most distant of the Galilean moons, has a significant impact on its internal structure, surface features, and overall evolution. The reduced tidal forces exerted on Callisto due to its distance result in a lack of significant internal heating and geological activity, leading to a heavily cratered surface and a relatively large amount of ice in its composition. This contrasts with the more geologically active moons, such as Io and Europa, which experience stronger tidal forces from Jupiter. The distance of Callisto from the planet also influences its orbital dynamics and resonance with the other Galilean moons, further shaping the evolution of this complex system.

Related terms

Galilean Moons: The Galilean moons are the four largest moons of Jupiter: Io, Europa, Ganymede, and Callisto. They were discovered by Galileo Galilei in 1610 and are the largest moons in the Solar System.

Tidal Forces: Tidal forces are the gravitational forces exerted by one body on another, which can lead to deformation and heating of the bodies involved. These forces play a significant role in the dynamics and evolution of the Galilean moons, including Callisto.

Orbital Resonance: Orbital resonance is a phenomenon where two or more orbiting bodies exert regular, periodic gravitational influence on each other, leading to their orbits becoming synchronized. This effect is observed in the Galilean moon system, including Callisto.