Jupiter is the fifth planet from the Sun and the largest in our solar system. Its mass is more than two and a half times that of all the other planets combined. It is the third brightest celestial object in the night sky after the Moon and Venus. As a gas giant, Jupiter is believed to have a rocky core composed of heavy elements, but, like other gas giants, it lacks a solid surface. It is renowned for its extremely rapid rotation, which causes it to have an oblate shape with bands and swirling clouds of ammonia and water storms, floating in an environment primarily made of hydrogen, with helium accounting for a quarter of its mass and a tenth of its volume. Jupiter is also home to the Great Red Spot, a massive storm larger than Earth that has been raging for hundreds of years. It has planetary rings like Saturn, though they are much fainter and composed of dust rather than ice. Jupiter’s strong magnetic field extends nearly to Saturn’s orbit and is observable from Earth. It generates more internal heat than it receives from the Sun.

Named after Jupiter, the king of the Roman gods, this planet is the largest in the solar system. The name was officially adopted in 1976 by the International Astronomical Union. Jupiter has been observed since ancient times due to its enormous size. It is orbited by 79 moons, with four discovered by the famous astronomer Galileo in the 17th century. One of these moons is larger than Mercury, while the other three are larger than Earth’s Moon. Some astronomers believe that Jupiter’s strong gravity shields Earth from long-period comets entering our solar system from outer regions, ejecting most of them back into space before they can approach Earth. Without Jupiter, these comets could potentially impact Earth, causing catastrophic collisions. However, this protection is not absolute, as Jupiter’s gravity also affects asteroids, potentially sending them towards the Sun and possibly towards Earth.

Size and Distance of Jupiter

Jupiter’s radius is 69,911 kilometers, making it 11 times larger than Earth. To put this in perspective, if Earth were the size of a coin, Jupiter would be the size of a basketball. It is an average distance of 778 million kilometers from the Sun, equivalent to 5.2 astronomical units (the distance from the Sun to Earth). Due to this distance, sunlight takes approximately 43 minutes to travel from the Sun to Jupiter.

Orbit and Rotation

Jupiter has the shortest day in the solar system, taking about 10 hours to complete one rotation. It orbits the Sun once every 12 Earth years (4,333 Earth days). Its equatorial tilt is only 3 degrees, which means Jupiter rotates almost perpendicular to its orbital plane, resulting in minimal seasonal variation compared to other planets.

Formation of Jupiter

Jupiter formed around 4.5 billion years ago, during the early solar system’s formation, when gravity pulled in gas and dust to create this gas giant. Jupiter accumulated most of the remaining mass after the Sun’s formation, ending up with more than twice the mass of all other solar system bodies combined. Jupiter’s composition is similar to that of stars, though it did not accumulate enough mass to ignite.

Structure of Jupiter

Jupiter’s composition is similar to that of the Sun, with most of its mass made up of hydrogen and helium. Due to high pressure and temperature, hydrogen is compressed into a liquid state. Scientists believe that, deep within Jupiter, the pressure is so great that hydrogen atoms are compressed into a metallic state, allowing it to conduct electricity. The planet’s rapid rotation drives electrical currents, generating its strong magnetic field. It remains unclear if Jupiter has a solid or liquid core, with estimates suggesting the core could be around 50,000 degrees Celsius and made mostly of iron and silicates.

As a gas giant, Jupiter does not have a solid surface. Its outer layers are mostly gases and liquids, making close exploration challenging. No spacecraft can land on Jupiter or fly through it safely, as extreme pressures and temperatures would crush, melt, or vaporize any spacecraft attempting to enter.

Jupiter’s appearance is characterized by a banded structure of colorful cloud patterns. It is believed to have three distinct cloud layers extending 71 kilometers thick: the upper layer is likely made of ammonia ice, the middle layer of ammonium hydrosulfide crystals, and the lower layer of water ice and vapor. The vibrant colors seen in Jupiter’s thick bands may be due to sulfur and phosphorus gases rising from the warmer interior, with the planet’s rapid rotation causing these gases to form dark belts.

The lack of a solid surface means that Jupiter’s atmospheric features, such as the Great Red Spot, can persist for many years. This giant storm, an oval-shaped vortex of clouds, is twice the size of Earth and has been observed for over 300 years. Data from NASA’s Juno spacecraft has provided clearer insights into what lies beneath Jupiter’s clouds, revealing that the planet’s cyclones are warmer at the top with lower density and cooler at the bottom with higher density. Anti-cyclones moving in the opposite direction are cooler at the top but warmer at the bottom. These storms are much more extensive than previously thought, with some extending up to 100 kilometers below cloud tops and the Great Red Spot reaching over 350 kilometers.

Magnetic Field

Jupiter’s magnetic field, known as the “magnetosphere,” extends between 1 to 3 million kilometers toward the Sun and gradually tapers into a tail stretching over a billion kilometers behind Jupiter. Jupiter’s magnetic field is 16 to 54 times stronger than Earth’s and interacts with charged particles near it, trapping and accelerating them to high energies that can damage spacecraft. This magnetic field also generates some of the most spectacular auroras in the solar system at Jupiter’s poles.

Potential for Life

Jupiter itself is unlikely to support life as we know it, due to its extreme temperatures, pressures, and materials. However, some of its moons, particularly Europa, are considered promising locations for finding life. Europa is believed to have a vast ocean beneath its icy crust that might support life.

Spacecraft Exploring Jupiter

Although Jupiter has been known since ancient times, Galileo Galilei was the first to make detailed observations of it using a small telescope in 1610. In recent years, Jupiter has been explored by various spacecraft and probes. Pioneer 10 and 11, and Voyager 1 and 2 were the first to fly close to Jupiter in the 1970s. The Galileo spacecraft was sent to orbit the gas giant, dropping a probe into its atmosphere. Cassini captured detailed images of Jupiter on its way to Saturn. New Horizons took additional images on its journey to Pluto and the Kuiper Belt. NASA’s Juno spacecraft, which arrived in Jupiter’s system in July 2016, is currently studying the giant planet from orbit.