Themisto

Alternative name: Also known as: S/1975 J 1

Moon
Themisto Radius

Radius of Themisto

The radius of Themisto is one of its most fundamental physical characteristics. The Themisto radius measures approximately 4 km, making it 1592.75× smaller than Earth. This measurement represents the average distance from the center of Themisto to its surface, providing crucial information about the celestial body's size and volume.

Understanding the Themisto radius is essential for calculating other important properties such as surface area, volume, and gravitational characteristics. The radius directly influences how we perceive and study this fascinating object in our Solar System.

Themisto Semi-Major Axis

Orbital Radius of Themisto

The Themisto semi-major axis is a critical orbital parameter that defines the average distance from the Sun. The Themisto semi-major axis measures 0.05 AU (approximately 7.51e+6 km), which represents the average orbital radius of Themisto. This measurement is fundamental to understanding Themisto's position in the Solar System and its relationship with other celestial bodies.

The orbital radius of Themisto determines how much solar radiation the planet receives, which directly influences its temperature, climate, and overall environmental conditions. This distance places Themisto in a specific region of the Solar System, each with unique characteristics and scientific significance.

When we examine the Themisto semi-major axis 0.05 AU, we gain insights into the planet's orbital mechanics, including its orbital period, velocity, and the gravitational forces at play. This parameter is essential for space mission planning and understanding the dynamics of our Solar System.

Themisto Mass

Mass of Themisto in kg

The Themisto mass is a fundamental property that determines many of the planet's physical characteristics. The mass of Themisto in kg is approximately 6.90e+14 kg, which is 8655072463.77× less than Earth's mass. This substantial mass creates a significant gravitational field that influences everything from atmospheric retention to orbital dynamics.

Understanding the Themisto mass allows scientists to calculate other critical properties such as surface gravity, escape velocity, and the planet's ability to retain an atmosphere. The mass also plays a crucial role in determining how Themisto interacts with other celestial bodies through gravitational forces.

The precise measurement of the mass of Themisto in kg is essential for space exploration missions, as it affects spacecraft trajectories, landing procedures, and the design of scientific instruments. This fundamental property helps us understandThemisto's formation history and its place in the evolution of our Solar System.

Themisto Orbital Period

How Long is a Year on Themisto?

The Themisto orbital period defines the length of one complete revolution around the Sun. The Themisto orbital period is 0.04 hours, which is 242717.65× shorter than Earth's year. This orbital period determines the length of Themisto's year and directly influences seasonal patterns, climate cycles, and temperature variations.

The Themisto orbital period is directly related to its distance from the Sun, following Kepler's laws of planetary motion. Planets farther from the Sun have longer orbital periods, while those closer complete their orbits more quickly. This relationship helps explain why Themisto takes the time it does to complete one full orbit.

Understanding the Themisto orbital period is crucial for space mission planning, as it affects launch windows, travel times, and the timing of scientific observations. This fundamental orbital parameter also provides insights into the planet's formation history and its current position in the Solar System's dynamic structure.

How Far is Themisto from Earth?

Distance Between Themisto and Earth

How far is Themisto from Earth? This is a question that fascinates both astronomers and space enthusiasts. The distance between Themisto and Earth varies throughout their orbital cycles, but on average, Themisto is approximately 1.42e+8 km(0.950 AU) away from Earth. This distance changes as both planets orbit the Sun, with the closest approach (opposition) and farthest separation (conjunction) creating significant variations.

The question "How far is Themisto from Earth?" has practical implications for space exploration. This distance determines travel time for spacecraft, communication delays for mission control, and the amount of fuel required for interplanetary missions. Understanding this distance is essential for planning future missions to Themisto.

The distance between Themisto and Earth is not constant due to the elliptical nature of both planets' orbits. When Themisto and Earth are on the same side of the Sun (opposition), they are at their closest, making this the optimal time for observations and potential missions. Conversely, when they are on opposite sides of the Sun (conjunction), they are at their farthest separation, which can exceed the average distance significantly.

Physical Properties
Mean Radius
4km
Equatorial Radius
4km
Polar Radius
0km
Mass
6.90e+14 kg
Volume
0.00e+0 km³
Density
1g/cm³
Gravity
0.003m/s²
Escape Velocity
0m/s
Flattening
0
Average Temperature
0.0 K (-273.1 °C)
Axial Tilt
0°
Semimajor Axis
7.51e+6km
Perihelion
5.91e+6km
Aphelion
8.87e+6km
Eccentricity
0.242
Inclination
43.08°
Sidereal Orbit
0.04 hours
Sidereal Rotation
0 seconds
Mean Anomaly
0°
Argument of Periapsis
0°
Longitude of Ascending Node
0°

Overview of Themisto

Themisto is a fascinating moon in our Solar System that has captured the attention of astronomers and space enthusiasts alike. With a Themisto radius of 4 km, making it 1592.8× 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 7.51e+6 km (0.050 AU) from the Sun, Themisto occupies a significant place in the Solar System's architecture. As a moon, Themisto demonstrates the incredible diversity of natural satellites that orbit larger celestial bodies throughout our Solar System.

Physical Characteristics

The Themisto physical characteristics reveal a world of remarkable dimensions and properties. The Themisto radius measures 4 km, making it 1592.8× smaller than Earth's size. The Themisto mass of 6.90e+14 kg represents 8655072463.8× smaller than Earth's mass, giving this world substantial gravitational influence. The Themisto density of 1 g/cm³ (5.5× smaller than Earth's density) provides clues about its internal composition, while the surface gravity of 0.003 m/s² (3382.8× smaller than Earth's gravity) determines how objects behave on its surface. The low density indicates a composition dominated by lighter elements, characteristic of gas giants or icy bodies.

Orbital Properties

The Themisto orbit reveals fascinating details about its journey around the Sun and its relationship to other Solar System objects. The Themisto orbit has a semimajor axis of 7.51e+6 km (0.050 AU), placing it 19.9× smaller than Earth's distance from the Sun. At its closest approach (perihelion), Themisto comes within 5.91e+6 km of the Sun, while at its farthest point (aphelion), it reaches 8.87e+6 km, creating a 39.5% variation in solar distance. The Themisto orbit is moderately elliptical with an eccentricity of 0.242 (14.5× Earth's orbital eccentricity), creating noticeable seasonal variations in solar radiation. The Themisto orbit takes 0.04 hours to complete (242717.7× smaller than Earth's orbital period), defining the length of its year. The orbital inclination of 43.08° indicates how much the Themisto orbit is tilted relative to the Solar System's ecliptic plane. This high inclination suggests Themisto may have experienced significant gravitational perturbations or formed in a different region of the Solar System.

Rotation and Tilt

The Themisto rotation and axial orientation provide crucial insights into its daily and seasonal cycles, as well as its orbital dynamics. The Themisto axial tilt of 0° determines the intensity and nature of seasonal variations. With minimal axial tilt, Themisto experiences virtually no seasonal changes, maintaining relatively constant temperatures throughout its year. The orbital orientation parameters reveal additional details about Themisto's position in space. The mean anomaly of indicates the planet's current position in its orbit relative to its perihelion. The argument of periapsis of shows how the orbit's orientation changes over time due to gravitational perturbations. The longitude of ascending node of defines the reference point where the orbit crosses the ecliptic plane.

Temperature and Atmosphere

The Themisto temperature and atmospheric conditions are fundamental to understanding its habitability and environmental characteristics. The Themisto average temperature of 0.0 K (-273.1 °C) (-459.7°F) provides the baseline for understanding its climate. These extremely cold temperatures make Themisto 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), Themisto presents a dramatically different thermal environment. Being closer to the Sun than Earth, Themisto receives more intense solar radiation, contributing to its temperature profile. The elliptical orbit creates significant temperature variations throughout the year, with extreme seasonal changes.

Escape Velocity & Flattening

The Themisto escape velocity and shape characteristics reveal important details about its gravitational field and rotational dynamics. The Themisto 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 Themisto to retain a substantial atmosphere. The Themisto 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.

FAQs About Themisto

What is the gravity on Themisto?

The gravity on Themisto is 0.003 m/s² (3382.8× smaller than Earth's gravity). This gravitational force determines how objects behave on the surface, affects atmospheric retention, and influences the planet's ability to hold onto gases and particles. A person weighing 70 kg on Earth would weigh 0.0 kg on Themisto.

How big is Themisto compared to Earth?

Themisto has a radius of 4 km, making it 1592.8× smaller than Earth's size. In terms of volume, Themisto is 0.0× the size of Earth. This size difference significantly impacts the planet's gravity, atmospheric retention, geological processes, and overall planetary characteristics.

How far is Themisto from the Sun?

Themisto orbits at an average distance of 7.51e+6 km (0.050 AU) from the Sun, placing it 19.9× smaller than Earth's distance from the Sun. This distance determines the amount of solar radiation the planet receives and significantly influences its temperature and climate.

How long is a year on Themisto?

A year on Themisto lasts 0.04 hours (242717.7× smaller than Earth's orbital period). This orbital period defines the length of the planet's year and affects seasonal patterns, temperature variations, and the overall climate cycle.

What is Themisto made of?

Themisto has a density of 1 g/cm³ (5.5× smaller than Earth's density). This density provides important clues about the planet's internal composition. The low density indicates a composition dominated by lighter elements, characteristic of gas giants or icy bodies.

Does Themisto have seasons?

Themisto has an axial tilt of . With minimal axial tilt, the planet experiences virtually no seasonal changes, maintaining relatively constant temperatures throughout its year.
Discovery Information
Discovered By
Charles Kowal 1975 - Scott S. Sheppard, David C. Jewitt 2000
Discovery Date
30/09/1975
Raw Data