What Is Jupiter Made Of?

Jupiter is the largest planet in our solar system by mass, size, and volume. It is the fifth planet from the sun at a distance of 484-million miles (778-million kilometers). By size, it is 86,880-miles (139,820-kilometres) in diameter, or about 11 times the size of Earth. Jupiter marks the first planet of the outer solar system, and it represents a complete change in planet type compared to the inner solar system. While the inner solar system contains rocky planets, Jupiter and the other outer planets are gas giants. Gas giants are significantly different from their rocky counterparts in terms of composition. While the rocky planets generally contain solid surfaces with an iron core, the gas giants are primarily composed of light elements such as hydrogen and helium. 

Composition Of Jupiter

Image of Jupiter taken by the Hubble telescope. Image credit: NASA/ESA

Jupiter is primarily composed of only two ingredients: hydrogen and helium. Hydrogen makes up roughly 90% of Jupiter’s total composition, while helium makes up nearly all of the remaining 10%. Elements and compounds heavier than hydrogen and helium comprise only a minuscule amount of what Jupiter is made of. Jupiter contains small amounts of water, methane, sulfur, carbon, nitrogen, and oxygen. Despite the rarity of these chemicals, they do play a significant role in the color and appearance of Jupiter’s atmosphere. For example, organic compounds might be the reason why Jupiter’s Great Red Spot is red, and differences in density between different chemicals helps to differentiate Jupiter’s atmosphere into separate layers. 

Liquid Hydrogen

Image of Jupiter taken by the Juno spacecraft. Image credit: NASA

Although hydrogen makes up 90% of Jupiter’s total composition, not all of Jupiter’s hydrogen comes in the form of a gas. Around 25,000-miles below Jupiter’s atmosphere, there exists a layer of liquid metallic hydrogen. Under the extreme pressures and temperatures of Jupiter’s interior, hydrogen gas takes the form of a metallic liquid. Although hydrogen is not a metal, it has some metallic properties when in liquid form. The most notable property is the fact that it can conduct electricity, and in turn generate a magnetic field. In fact, it is this layer of liquid metallic hydrogen that is responsible for the formation of Jupiter’s massive magnetic field, which is the strongest of any other planet in the solar system and second in strength only to the sun’s magnetic field. 

Jupiter’s Atmosphere

Jupiter’s atmosphere
Up-close view of Jupiter's upper atmosphere taken by the Juno spacecraft. Image credit: NASA

The atmosphere of Jupiter is divided into four separate layers: troposphere, stratosphere, thermosphere and exosphere. The exosphere is the outermost layer and the troposphere is the innermost layer. In between these layers is the surface of Jupiter. However, it is important to note that the surface is not solid like it is on Earth. Rather, the surface of Jupiter is defined as the region where atmospheric pressures are equal to that on Earth’s surface. Rather than being solid, the surface of Jupiter is gaseous. Furthermore, it is within these atmospheric layers that Jupiter’s massive storm systems form, such as the famous Great Red Spot. Heat from Jupiter’s interior rises through the process of convection, wherein heat is transferred from the interior and the atmosphere. This heat results in the formation of the solar system’s largest storms, some of which can continue raging for hundreds of years. 

Jupiter’s Core

Great Red Spot
Juno took this running image of Jupiter and its Great Red Spot while orbiting the giant planet. Image credit: NASA

The interior of all the gas giants are among the most mysterious places in the solar system. This is simply due to the fact that the layers beneath the upper atmosphere are hidden from view, and while some spacecraft have plummeted through the atmosphere of some gas giants, they have been crushed by the atmospheric pressure before making it far into the interior. Interestingly, the core of Jupiter is perhaps its biggest mystery. As of yet, astronomers do not know whether Jupiter has a solid core or not. While Jupiter is believed to have had a core in the past, it remains unknown whether or not that solid core has eroded over time. Jupiter could still possess a solid core of rock and metal, or the core may have eroded away and is now composed of gas. Evidence from NASA’s Juno spacecraft suggests that the core may actually be a partially solid, partially gaseous object that is in the process of eroding and melting. 

Like A Star

The Sun
Jupiter's composition is very similar to that of the sun. Image credit: NASA/SDO

Jupiter’s composition is believed to be very similar to the solar nebula that formed our solar system 4.5-billion years ago. Interestingly, Jupiter’s composition is remarkably similar to the sun and other stars. If Jupiter were to increase its mass by a factor of around 60, it's entirely possible that pressures in its core would become high enough to ignite nuclear fusion, allowing Jupiter to become a main sequence star. Due to Jupiter’s composition, it is often referred to as a failed star, yet it has actually never come anywhere near massive enough for nuclear fusion to occur. 

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