Solar Exploration

Jupiter is by far the largest planet in the solar system — more than twice as massive as every other planet combined — and its gravity has shaped the solar system's architecture, flinging comets and asteroids out of the inner planets' path over billions of years. It rotates faster than any other planet, completing a full spin in under ten hours, which whips its atmosphere into the distinctive colored bands visible through even a small telescope.

Its most famous feature, the Great Red Spot, is a storm larger than Earth that has raged for at least 190 years and possibly much longer. Jupiter also hosts the four large Galilean moons — Io, Europa, Ganymede and Callisto — discovered by Galileo Galilei in 1610, a discovery that helped prove not everything in the sky orbits Earth.

Beneath its swirling cloud tops, Jupiter has no solid surface to speak of — the atmosphere gradually compresses into a scalding ocean of liquid metallic hydrogen thousands of kilometers deep, surrounding a dense core of rock, ice and metal several times Earth's mass. That metallic hydrogen layer, an exotic state of matter created only under extreme pressure, generates the strongest magnetic field of any planet in the solar system, trapping intense radiation belts that make close exploration hazardous for spacecraft electronics.