Titan, Saturn’s largest moon, is often described as planet-like due to its thick atmosphere and evidence of stable surface liquids. It is the second-largest moon in the Solar System, trailing only Jupiter’s Ganymede. While Titan may seem large among moons, its size and composition reveal a significant contrast with Earth. This comparison highlights differences in their dimensions, internal structure, and gravitational influence.
Comparing Titan and Earth’s Physical Dimensions
Titan is considerably smaller than Earth when considering linear measurements. The moon has a mean diameter of approximately 5,150 kilometers, which is less than half of Earth’s diameter of about 12,742 kilometers.
This smaller diameter translates into a much reduced surface area for Titan. The total surface area of Titan is only about 83.3 million square kilometers, which is a fraction of Earth’s surface area of 510 million square kilometers. To put this difference into perspective, Earth’s surface is approximately six times larger than Titan’s. Although Titan is a giant among moons, it remains a comparatively small globe next to a terrestrial planet like Earth.
Mass, Density, and Gravitational Differences
The disparity in size becomes even more pronounced when comparing mass and density, which are measures of a body’s internal composition. Titan is only about 2.25% as massive as Earth, meaning Earth contains over 44 times the amount of material.
This significant mass difference is primarily due to a lower overall density on Titan. Titan’s mean density is about 1.88 grams per cubic centimeter, while Earth’s is much higher at 5.51 grams per cubic centimeter. This low density indicates that Titan is composed of a mixture of rock and a substantial proportion of water ice, with estimates suggesting 40–60% rock and the rest being ice and other materials. Earth, by contrast, has a dense metallic core that contributes significantly to its higher mass and density.
The difference in mass directly impacts the surface gravity of the two worlds. Titan’s surface gravity is only about 1.35 meters per second squared, which is roughly 14% of Earth’s gravity. This weak gravitational pull is what allows Titan to maintain an atmosphere that extends to a height ten times greater than Earth’s, despite the moon’s smaller size. Standing on Titan would feel dramatically different, with objects weighing much less than they do on Earth.
Titan’s Scale Relative to Other Solar System Bodies
Titan is the second-largest moon, only slightly smaller than Jupiter’s Ganymede. It is approximately 50% larger in diameter than Earth’s own Moon.
The scale of Titan is so large that it actually exceeds the size of a major planet. With its diameter of 5,150 kilometers, Titan is larger than the planet Mercury, which has a diameter of about 4,880 kilometers. This unique characteristic makes Titan a truly planet-like moon, even though it is only 40% as massive as Mercury because of its icy, lower-density composition. Titan’s size places it among the largest solid bodies in the Solar System.