The fourth brightest object in the sky and the fifth planet from the Sun, Jupiter takes about 11.8 earth years to complete one orbit around the Sun. Also, Jupiter takes approximately 9 hours and 55 minutes to rotate around itself. However, these speedy rotations exert a very strong magnetic field around Jupiter that makes it the strongest among all planets. Jupiter gets an oblate shape because of the rapid rotation that flattens the planet slightly. Hence, it has the shortest day of all the planets. Its distance from the Sun is about 778,340,821 km. Generally, this planet is referred to as The Giant as it has 62 moons and is the largest with a radius of about 71,500. Jupiter has a high gravity and therefore weights on Earth get magnified two and a half times on Jupiter. 

Spanning an altitude of over 5000 km, Jupiter has the largest planetary atmosphere in the solar system. It does not have any surface and hence its base is referred to as the point at which the atmospheric pressure is equal to 10 times the surface of the Earth. There are high velocity winds at the Jupiter and other gas planets, which are confined in wide bands of latitude. These winds blow in opposite directions. However, the colour of the bands that dominate the planet’s appearance is due to the slight chemical and temperature differences between them. The light coloured bands are called zones whereas the dark ones are called belts. These belts and zones, divided in the upper atmosphere, are primarily made of ammonia crystals, sulphur, and mixtures of the two compounds. The dust particles ejected from some of Jupiter’s smaller worlds during impacts from incoming comets and asteroids form the ring system for the Jupiter. This system starts at about 92,000 km above the Jupiter’s cloud tops and stretches out to more than 225,000 km from the planet. They are about 2,000–12,500 km thick. The atmosphere of Jupiter, similar to Sun, is composed of mostly Hydrogen and Helium. The Hydrogen gas is compressed into a liquid as the temperature and pressure increase. This, however, gives Jupiter a largest ocean – the one that is made of Hydrogen instead of water. 

As discussed earlier, Jupiter is a gas giant and does not have a solid surface. However, as there is no solid surface to slow the spots down, they can persist for many years. It contains liquid hydrogen and some water. The gaseous atmosphere merges gradually into the liquid surface. We all know about the Great Red Spot in the Jupiter. It is a huge storm on Jupiter and has raged for more than 300 years. It is of an oval shape of about 12,000 by 25,000 km which is big enough to hold two Earths in it. According to some observations, the Great Red Spot is a high-pressure region whose cloud tops is higher and colder than the surrounding regions. 

A ball of gas, Jupiter is a dense core with a mixture of elements. Its body is made entirely of Hydrogen and Helium. It is surrounded by a layer of liquid metallic hydrogen and helium, and has an outer layer of molecular hydrogen. Its mean density is not more than that of water. Despite it being the largest ocean of Hydrogen in the solar system, there is a considerable uncertainty. The core of the Jupiter is rocky but its detailed composition like the properties of materials and temperatures are still unknown. Jupiter has a lot of internal heat and it emits more energy than it receives from the Sun. The basic difficulty in constructing a model that will adequately describe the internal conditions for Jupiter is the absence of extensive laboratory data on the properties of hydrogen and helium at pressures and temperatures that would exist near the centre of this giant planet. The central temperature is estimated to be close to 24,700°C for Jupiter that enables it to emit with about twice as much energy as it receives from the Sun. 

There are about 67 natural satellites of Jupiter. Out of these, 51 are less in diameter. However, there are four largest and most well known moons of Jupiter that were discovered by Galileo in the year 1610. They are also known as the ‘Galilean Moons’. They include:

• Io: Its surface is covered by sulphur and is the most volcanically active body in the solar system. Its volcanoes are driven by hot silicate magma. These volcanoes are generated because Jupiter’s immense gravity causes ‘tides’ in its solid surface as Io travels in its slightly elliptical orbit.
• Europa: This moon has a potential for having a ‘habitable zone’ because life forms have been found thriving near the volcanoes on Earth and in other extreme locations. Its surface is mostly water ice and is thought to have twice as much water as Earth.
• Ganymede: It is the only moon that has its own internally generated magnetic field and is hence the largest moon in the solar system.
• Callisto: Its surface is heavily cratered and ancient and very few small craters on Callisto show a small degree of current surface activity.

Some of the other moons are Adrastea, Ananke, Carme, Elara, Himalia, Leda, Lysithea, Metis, Pasiphae, Sinope and Thebe.

Jupiter is believed to bestow success. The one who is favoured by Jupiter commands respect. Hindus regard it as Guru, it’s significant because of its large size. It is said to be powerful and can counter the ill effects of other planets. According to the Greeks, Jupiter, also known as Zeus, overthrew his father Saturn to become the king of Gods. With the help of his brothers Neptune and Pluto he split the Universe.

Explaining the origin of Jupiter is tantamount to explaining the origin of the Universe. The gradual development of the Sun and planets from a huge cloud of gas and dust containing gravitational instabilities had caused the cloud to collapse. Hence, missions continue to be sent there for information. Knowledge about Jupiter suddenly increased since the mid-1970s when three consecutive missions were sent there namely Pioneers 10 and 11 in 1973–74, Voyagers 1 and 2 in 1979, and the Galileo orbiter and probe, which reached Jupiter in December 1995. In 2000, the spacecraft Cassini flew by Jupiter on its way to Saturn and sent some more information. A similar spacecraft New Horizons flew by Jupiter in 2000, on its way to Pluto.