Jupiter

The largest planet in the Solar System, and the first of the gas giants. Learn more about the Jovian planet here!

Formation

The formation of the gas giants is controversial and shrouded in mystery. Models of a young Jupiter suggest that the core of the planet formed in the Solar nebula before the ignition of the Sun, gaining a core of up to 20 Solar masses. As the core gathered mass, it gathered the gases that made up its atmosphere to create the gas giant observed today. Another model suggests that Jupiter formed very close to the Sun, near the present day Mars orbit, and over time formed a resonance with the orbit of Saturn, pushing the orbits of the two gas giants back to their present day positions. As the two gas giants migrated outwards, Jupiter would have gathered large quantities of gas forming its atmosphere. Still yet other models suggest that Jupiter formed further out compared to its present orbit, near the present day Uranus orbit, and migrated inwards. Much is still yet to be learned about the formation of the gas giants and Jupiter.

Composition

The composition of Jupiter is thought to be similar to the composition of the young Solar nebula. Around 75% of the atmosphere is composed of hydrogen, 24% helium, and 1% other elements such as oxygen, nitrogen, carbon, and sulfur. The interior of Jupiter is mostly the same, except hydrogen is at 71% composition, helium at 24% composition, and the rest is composed of more massive elements and molecular compounds.

Structure

As a gas giant, Jupiter has a structure that is more similar to that of the Sun than Earth. The core of Jupiter is debated to be either a solid core or a more diffuse core that is too hot to be solid. Surrounding the core is believed to be a large layer of metallic hydrogen, with electrical currents flowing and creating the strong magnetic field surrounding Jupiter. Above this layer of metallic hydrogen is liquid hydrogen, with possible helium and neon droplets falling to the middle of the planet. Finally at the outermost edge of the planet is the atmosphere.

Atmosphere

The atmosphere of Jupiter is made up of mostly hydrogen, with water ice and ammonia clouds. These clouds are formed in prominent bands that circle the planet from North to South. Giant storms form on Jupiter, with the most famous being the great red spot, seen since the early nineteenth century. Pearl strings also form in a series of storms, ranging from 4 to 9 separate systems in the same band since the nineteen eighties. At the poles, hexagonal storms form and try to migrate towards their respective poles. The storm that is already at the pole keeps the other hexagonal storms at bay, causing them to last in both their position and longevity.

Magnetic Field

The magnetic field of Jupiter is the largest of the planets in the Solar System. Believed to be caused by the metallic hydrogen layer located within the planet, the magnetic field is so powerful that auroras are constantly occurring on Jupiter’s poles. The magnetic field stretches from 75 Jovian radii towards the Sun, with the tail reaching the orbit of Saturn. With the four main Galilean moons located inside the magnetic field of Jupiter, they are all protected from Solar radiation reaching their surfaces.

Planetary Rings

Jupiter has a main ring that consists of three primary bands composed of dust. The first and third of these bands are possibly associated with the moons Metis and Adrastea, respectively, with the middle having no known satellite affiliation. Impacts on these moons supply the ring with dust, keeping the ring from disintegrating. Jupiter also has a so-called halo that is shaped like a donut, but less bright compared to the main ring. Finally, a gossamer ring exists in two components, believed to be supplied by the moons Thebe and Amalthea.

Satellites

Pioneer 10 and 11 were the first satellites to visit Jupiter, performing flyby maneuvers. Recording the first detailed images of the planet, these satellites were able to better refine the measurements of the planets size and mass, along with crucial radiation measurements.

Voyager 1 and 2 both performed flyby maneuvers of Jupiter, studying the Galilean moons and discovering the faint ring system. The great red spot was observed to have changed since the Pioneer missions, and was observed to be a high-pressure system. Io was also observed to have debris trailing from the moon’s surface, leading to the discovery of volcanism on Io.

The first satellite to orbit Jupiter was Galileo, making it the first satellite to orbit an outer Solar System planet. Galileo was able to make flybys of the Galilean moons, revealing the extensive volcanism on the surface of Io, the possible water ocean on Europa, and the magnetic field around Ganymede. A probe from the mission was also sent into the Jovian atmosphere, recording data for almost an hour before being lost. Galileo was the first, and only, satellite to observe a comet colliding with another planet when Shoemaker-Levy 9 crashed into Jupiter. At the end of the mission, Galileo was sent into the atmosphere of Jupiter as well in order to prevent contamination of possible life on Europa.

The second satellite to orbit Jupiter is Juno, entering a polar orbit around the planet for the first time. Cameras onboard Juno were able to capture the poles of Jupiter, revealing strong arouras thanks to the magnetic field, and hexagonal weather storms. Juno is able to measure the radiation emanating from the atmosphere, as well as the strength of the polar magnetic field. Refinements on the core mass and gravity of Jupiter will be made as well. Planned flybys of three Galilean moons are still to come for Juno, followed by eventually disintegrating into Jupiter’s atmosphere.