Iapetus

Iapetus is a fascinating moon in our Solar System that has captured the attention of astronomers and space enthusiasts alike. With a Iapetus radius of 1,471.2 km, making it 4.3× smaller than Earth's size, this celestial body presents unique characteristics that distinguish it from other objects in our cosmic neighborhood. Positioned at an average distance of 3.56e+6 km (0.024 AU) from the Sun, Iapetus occupies a significant place in the Solar System's architecture. As a moon, Iapetus demonstrates the incredible diversity of natural satellites that orbit larger celestial bodies throughout our Solar System.

The Iapetus physical characteristics reveal a world of remarkable dimensions and properties. The Iapetus radius measures 1,471.2 km, making it 4.3× smaller than Earth's size. The Iapetus mass of 1.81e+21 kg represents 3308.6× smaller than Earth's mass, giving this world substantial gravitational influence.

The Iapetus orbit reveals fascinating details about its journey around the Sun and its relationship to other Solar System objects. The Iapetus orbit has a semimajor axis of 3.56e+6 km (0.024 AU), placing it 42.0× smaller than Earth's distance from the Sun. At its closest approach (perihelion), Iapetus comes within 3.46e+6 km of the Sun, while at its farthest point (aphelion), it reaches 3.66e+6 km, creating a 5.7% variation in solar distance. The Iapetus orbit is nearly circular with an eccentricity of 0.028 (1.7× Earth's orbital eccentricity), resulting in relatively stable solar heating throughout its year. The Iapetus orbit takes 0.02 hours to complete (397808.5× smaller than Earth's orbital period), defining the length of its year. The orbital inclination of 14.72° indicates how much the Iapetus orbit is tilted relative to the Solar System's ecliptic plane. This moderate inclination indicates a typical orbital evolution for objects in this region of the Solar System.

The Iapetus rotation and axial orientation provide crucial insights into its daily and seasonal cycles, as well as its orbital dynamics. The Iapetus rotation period of 0.48 hours (49.6× smaller than Earth's rotation period) determines the length of its day. This extremely fast rotation creates intense centrifugal forces and may contribute to the planet's flattened shape. The Iapetus axial tilt of 0° determines the intensity and nature of seasonal variations. With minimal axial tilt, Iapetus experiences virtually no seasonal changes, maintaining relatively constant temperatures throughout its year. The orbital orientation parameters reveal additional details about Iapetus's position in space. The mean anomaly of 0° indicates the planet's current position in its orbit relative to its perihelion. The argument of periapsis of 0° shows how the orbit's orientation changes over time due to gravitational perturbations. The longitude of ascending node of 0° defines the reference point where the orbit crosses the ecliptic plane.

The Iapetus temperature and atmospheric conditions are fundamental to understanding its habitability and environmental characteristics. The Iapetus average temperature of 0.0 K (-273.1 °C) (-459.7°F) provides the baseline for understanding its climate. These extremely cold temperatures make Iapetus inhospitable to life as we know it, with any atmosphere likely frozen solid on the surface. Compared to Earth's average temperature of 15°C (59°F), Iapetus presents a dramatically different thermal environment. Being closer to the Sun than Earth, Iapetus receives more intense solar radiation, contributing to its temperature profile.

The Iapetus escape velocity and shape characteristics reveal important details about its gravitational field and rotational dynamics. The Iapetus escape velocity of 0 m/s determines how easily objects can break free from its gravitational pull. This relatively low escape velocity means that gases and light molecules can easily escape into space, making it difficult for Iapetus to retain a substantial atmosphere. The Iapetus flattening of 0.0000% indicates how much the planet's rotation affects its shape. This minimal flattening suggests a nearly spherical shape, indicating either slow rotation or a very rigid internal structure.