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
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.
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.
Like a Star
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.
