Related Experiment Video
Updated: Jun 26, 2026
11:34
Scattering And Absorption of Light in Planetary Regoliths
Published on: July 1, 2019
Summary
Radioactive decay from elements like potassium and uranium keeps outer planet moons, such as Callisto, warm internally. This internal heat maintains a liquid mantle beneath an icy crust, suggesting potential subsurface oceans.
Area of Science:
- Planetary Science
- Astrobiology
- Geophysics
Background:
- Outer planet satellites are icy bodies with complex internal structures.
- Internal heat sources are crucial for maintaining liquid water and geological activity.
Purpose of the Study:
- To model the steady-state thermal structure of large outer planet satellites.
- To investigate the role of radiogenic heating in maintaining internal temperatures.
Main Methods:
- Development of steady-state thermal models.
- Analysis of heat generated by long-lived radioisotopes (potassium, uranium, thorium).
Main Results:
- Internal temperatures are significantly above the ice-ammonia eutectic point due to radioactive decay.
- Callisto exhibits a thermal structure with an icy crust, a liquid mantle, and a dense core.
- The core is composed of hydrous silicates and iron oxides.
Conclusions:
- Radiogenic heating is a primary driver for maintaining internal warmth in large outer planet moons.
- The modeled structure of Callisto suggests a differentiated interior with a potentially habitable subsurface ocean.
Related Concept Videos
01:24Acceleration due to Gravity on Other Planets
The gravitational acceleration of an object near the Earth's surface is called the acceleration due to gravity. It can be measured by conducting simple experiments on Earth. However, such an experiment is impossible to conduct on the surface of other planets.
Astronomical observations are thus used to measure the acceleration due to gravity on other planets. This can be determined by observing the effect of a planet's gravity on objects close to it. The crucial factor that helps in this...
Astronomical observations are thus used to measure the acceleration due to gravity on other planets. This can be determined by observing the effect of a planet's gravity on objects close to it. The crucial factor that helps in this...
01:16Circular Orbits and Critical Velocity for Satellites
The Moon orbits around the Earth. In turn, the Earth (and other planets) orbit the Sun. The space directly above our atmosphere is filled with artificial satellites in orbit. One can examine the circular orbit, the simplest kind of orbit, to understand the relationship between the speed and the period of planets and satellites with respect to their positions and the bodies that they orbit.
Nicolaus Copernicus (1473-1543) first suggested that the Earth and all other planets orbit the Sun in...
Nicolaus Copernicus (1473-1543) first suggested that the Earth and all other planets orbit the Sun in...
01:11Energy of a Satellite in a Circular Orbit
Thousands of artificial satellites orbit the Earth every day at various distances from the Earth. Satellites that orbit the Earth below an altitude of 1,600 km are considered to be orbiting in low-Earth orbit (LEO). Research satellites and Earth observation satellites are usually placed in LEO, and mostly orbit the Earth in elliptical orbits. Navigation satellites are placed in medium-Earth orbit (MEO), ranging from 2,000 km to 36,000 km from the surface of the Earth. Meanwhile, communication...
01:10Kepler's First Law of Planetary Motion
In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. He formulated his first two laws based on the observations of his forebears, Nikolaus Copernicus and Tycho Brahe.
Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
On the other hand,...
Polish astronomer Nikolaus Copernicus put forth a theory that stated a heliocentric model for the solar system. According to this heliocentric theory, all the planets, including Earth, orbit the Sun in circular orbits.
On the other hand,...
01:29Kepler's Second Law of Planetary Motion
In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. His first law states that all planets orbit the Sun in an elliptical orbit, with the Sun at one of the ellipse's foci. Therefore, the distance of a planet from the Sun varies throughout its revolution around the Sun.
While in an elliptical orbit, the total energy of the planet is conserved. Therefore, the planet slows down when it is at apogee and...
While in an elliptical orbit, the total energy of the planet is conserved. Therefore, the planet slows down when it is at apogee and...
01:18Kepler's Third Law of Planetary Motion
In the early 17th century, German astronomer and mathematician Johannes Kepler postulated three laws for the motion of planets in the solar system. In 1909, he formulated his first two laws based on the observations of his forebears, Nikolaus Copernicus and Tycho Brahe. However, in 1918, he published his third law of planetary motion, which gives a precise mathematical relationship between a planet's average distance from the Sun and the amount of time it takes to revolve around the Sun. It...