Tidal Forces within the Planet Jupiter
Keplers Third Law (captures the relationship between the distance of planets from the Sun, and their orbits) can be used to describe the orbits of the planets and its moons. These objects can be considered gravitational point sources where the moons position relative to the planet can be determined by applying Newton’s law of gravity to the center of the moon and the center of the planet.
The inverse square force of gravity is different between points on the near sides of two objects and the forces on their opposite sides. The near point is being pulled more strongly toward earth, while the far point is being pulled less strongly. Relative to the center, which determines the moons orbital position, the near point is pulled toward the planet, while the far point is pushed away from the planet. The difference is what gives rise to Strong Gravitational forces within the planet Jupiter.
An example of this would be the force the moon exerts on the earth which leads to the rise and fall of the oceans along our coast. Each body is stretched along an axis pointing toward the other, with the near side being pulled closer and the far side being stretched away resulting in a bulge on both the near and far sides.
Within the Galilean moons of Jupiter, the four biggest moons, IO, Europa, Ganymede and Callisto tides have played a significant role in shaping its surfaces densities. Callisto the farthest of the four biggest moons from Jupiter has a low density of 1.8 times that of water. Ganymede has a density of 1.9 times that of water. Europa has a density 3.5 times that of water. The difference is due to Jupiter’s strong gravity and also to the specific orbits of the moons, with distance the tidal forces drop off considerably. These forces play key roles in shaping the surfaces of Jupiter’s moons. Callisto which is the farthest away has minimal tidal effects, has a composition of primarily rock and water has a frozen surface which has stayed relatively the same. The tidal stresses on Ganymede caused a grooved terrain of buckled ice sheets. Europa with its active surface due to its interior heat caused by its tidal stresses keeps the water in its interior liquid. Io which is closest to Jupiter has a completely molten interior and active volcano surface, due to its interior heating caused by its large tidal stresses keeps the water in its interior liquid.
Tidal strain is the difference in gravity from one side to the other on a moon. If that difference in gravity is to high it will tear the moon apart. That threshold is called the Roche Limit. This is the distance from the planet where the gravity is so strong on the planet it is torn apart, such as the rings of Saturn. Saturn has many icy particles in the shape of a ring orbiting its planet, and most particles are the consequence to be considered a moon if they fall within this Roche Limit.
Tidal effects could also be a significant factor for the geyser plumes seen on the surface of Neptune’s moon Triton as Voyager 2 passed the planetary system. The Neptune-Triton gravitational bond acting at a high inclination to the Neptune equator and the fact that Neptune was a fluid body with significant oblateness (elliptical spheroid) would produce tidal and mechanical forces that are transformed into thermal energy coming through as geyser plumes on Triton’s surface.
Geo-potential is seen on the surface of the planets as winds on the outer planets. These winds are small in comparison to the planets linear speed of rotation on these planets. This potential can be contributed to the tidal forcing of the outer planets moons. Estimates for the outer planets wind magnitudes are Jupiter 120 m/s, Saturn 450 m/s, Uranus 200 m/s and Neptune 400 m/s. These wind speeds are for the upper atmosphere of these planets. These are considered gaseous planets with no clear distinction of solid surfaces.
Tidal geo-potential created by the planets moons is greater than the Earth–Moon tidal geo-potential. Jupiter – Io is 116 times greater than the Earth-Moon, while Neptune-Triton is 36 times greater and Saturn-Titan and Uranus-Ariel are 5 and 3 times greater respectively.