The biggest planet in the Solar System, Jupiter, is nearly 780 million kilometers away from the Sun. Apart from Venus and Mars, it is the brightest object in the sky. It is so huge that, more than 1300 Earths could be contained inside it. But its size is deceptive. It is only about 300 times as heavy as the Earth, but it is less dense. Jupiter is, in fact, is a giant gas planet. It’s extremely dense and relatively dry atmosphere is composed of a mixture of hydrogen, helium and much smaller amounts of two poisonous gases, methane and ammonia. The same mixture of elements have also made up the Sun.
The planet is covered in thick red, brown, yellow and white clouds. The clouds make the planet look as if it has stripes. The atmosphere of Jupiter is probably a few hundred miles in depth, pulled toward the surface by the intense gravity. Closer to the surface, the gases become more dense and likely turn into a semi liquid compound.
Pioneers 10 and 11 found evidence that the planet itself is composed almost entirely of liquid hydrogen and probably there is no actual interface between the atmosphere and surface. Jupiter's rocky core lies well below the ‘surface’ and is very hot , around 19982º C, due to gravitational compression. But Jupiter is much too small and cool to ignite nuclear fusion reactions, which are required to become a star. The temperature in the clouds of Jupiter is about - 145º C and the core temperature is much hotter, may be about 24,000º C, which is hotter than the surface of the sun.
Jupiter rotates or spins faster than any other planet and it takes only about 10 hours to complete one rotation on its axis. Its orbit around the sun is elliptical and it takes 12 Earth years to make one revolution around the sun, which means, one year on Jupiter is equal to 12 years on Earth.
Jupiter's extremely fast rotation flattens the globe at the poles, which is responsible for the extremely changeable weather patterns in the enveloping clouds of the planet. Those clouds are considered to be made of ammonia ice crystals, changing to ammonia droplets further down. It is estimated that the temperature of the cloud top is about -173.33 C., while Jupiter's average temperature is -145’56º C. Since Jupiter is only tilted slightly more than 3 degrees on its axis, seasonal fluctuations are minimal.
Jupiter has 63 known satellites, which circle in different orbits. Four of them are roughly the size of our Moon. Ganymede, the largest one, is larger than the planet Mercury. Jupiter also has three thin rings that are difficult to see. NASA’s Voyager I spacecraft discovered the rings in 1979. The rings are made up mostly of tiny dust particles. One of Jupiter’s most famous features is the Great Red Spot, which has raged for at least 350 years. It is a turbulent whirlpool of wind, a persistent anticyclonic giant storm,
resembling a strong hurricane on Earth, but much larger. It is a storm of about 20,000 kilometers long and 12,000 km wide, about two to three times larger than Earth. Since the cooler gas is heavier, it tends to move downwards through the atmosphere. In the said continuous process, the swirling intensifies, but there is no solid ground on Jupiter to slow it down. As a result, when the swirling gases merge into one another, they create giant circling storms. Astronomers believe that several giant storms came simultaneously and formed the Giant Red Spot. At its widest point, it is more than twice the size of Earth. The Great Red Spot with tumultuous winds peaking at about 400 mph, has been swirling wildly over Jupiter’s skies for the past 150 years, or even more. However, even today, scientists still struggle to learn what causes its swirl of reddish hues.
The Magnetic field of Jupiter is nearly 20,000 times stronger than Earth's.