Far more massive than all the other planets combined, this magnificent gas giant graces the night sky as a guardian of the solar system. Named after the principal god of Roman mythology, it was known since prehistoric times and viewed as a symbol of power and dominance.
Jupiter is the fifth planet from the Sun and it is among the brightest objects visible on the night sky, often mistaken for a star. Though it was known as a wandering star since ancient times, it remained shrouded in mystery until Galileo pointed his telescope at it in 1610. He discovered that the planet formed a microsystem of its own, containing the four moons named Callisto, Europa, Ganymede and Io. In time, more satellites were discovered, reaching a staggering number of 63.
The planet is made of 90% hydrogen and 10% helium, with small amounts of methane, ammonia, silicon-based compounds and water vapor. Because it is primarily made of gas, it is far less dense than rocky planets like the Earth or Mars. Jupiter has a solid internal core, containing a mixture of elements, including metallic hydrogen. The exact composition of the core is subject to speculation, because the properties of materials at such conditions of pressure and temperature are yet to be unraveled by scientists.
Jupiter has a simple system of rings, composed of dust particles. Unlike Saturn's bright, impressive rings, Jupiter's are dark and faint; thus, they are invisible from the Earth. They were discovered in 1979 by Voyager 1, at the insistence of scientists to take a closer look and check for the presence of rings. Their existence came as a total surprise to the scientific community.
The weather on Jupiter has powerful patterns. Because of its dense atmosphere rotating rapidly, gigantic storms can grow in as little as one day. The most remarkable storm on Jupiter is known as The Great Red Spot. It has lasted for more than three centuries and it is the most powerful storm in the whole solar system. Jupiter's dark and bright stripes are so surprisingly stable that astronomers were able to name them.
Because of its incredible gravity well, Jupiter is often seen as the protector of the inner solar system. It shields Earth and the inner rocky planets from comets and asteroids that could otherwise impact them. This has greatly reduced the frequency of mass extinctions on our planet, thus helping more complex life forms to develop.
The existence of life on Jupiter is seen as highly unlikely, because of its extreme weather. However, the presence of lightning and the chemical compounds present in the atmosphere could support very simple life forms, similar to the plankton found in Earth's seas.
Despite being visited by several spacecrafts like Pioneer 10, Pioneer 11, Voyager 1, Voyager 2, Ulysse and Galileo, the mighty gas giant still has many more secrets to reveal such as its origins and formation, the existence of a solid core and magnetospheric dynamics.