With dozens of moons and an enormous magnetic field, Jupiter – the most massive planet in our solar system – forms a kind of miniature solar system.

Not a solid planet.  Not quite a star. Jupiter is one of those half-way stellar oddities where nuclear fusion failed to start and remains a giant mass of cool gas held together by gravity.

Jupiter resembles a star in its composition, but it did not grow quite big enough and failed to ignite nuclear fusion.  The planet’s swirling cloud stripes are punctuated by massive storms such as the Great Red Spot, which has raged for hundreds of years.

Jupiter is a gas-giant planet and it does not have a solid surface.  However, it is predicted that Jupiter has an inner, solid core about the size of the Earth.  Its atmosphere is mostly made up of molecular hydrogen (H₂) and helium (He).

Jupiter is the fifth planet from the Sun at a distance of about 778 million km (484 million miles) or 5.2 AU.  It completes its orbit around the Sun in about 12 Earth years (4,333 Earth days) – a year in Jovian time.