About Jupiter

Planet Profile

This color-enhanced image of Jupiter was taken by Voyager 1.

Jupiter, named after the king of the Roman Gods, reigns supreme among the nine planets of our solar system, rivaling the Sun in its grandeur. Giant Jupiter contains two-thirds of the planetary mass of the solar system. In composition it resembles a small star. Its interior pressure may reach 100 million times the surface pressure on Earth. Jupiter's magnetic field is immense, even in proportion to the size of the planet, stretching millions of miles into the solar system. If the magnetic field were visible, it would rival the apparent size of our Moon. Electrical activity in Jupiter is so strong that it pours billions of watts into Earth's own magnetic field every day. No planet has greater influence on its neighbors.

Endowed with 16 known moons, a ring system, and an immense, complex atmosphere, Jupiter is the innermost of the 4 giant planets (the others are Saturn, Uranus, and Neptune), and clearly the most dynamic. Its atmosphere bristles with lightning and swirls with huge storm systems including the Great Red Spot, a storm that has persisted for at least 100---and perhaps as long as 300---years. With its dynamism, huge energy output, and entourage of satellites, Jupiter is in many ways like a small sun, and the Jovian system resembles a miniature solar system. Although Jupiter is a stellar composition----most of its mass is hydrogen and helium---it does not burn like the Sun. Models of star formation suggest that Jupiter's mass is only about one-eightieth of the mass needed for ignition, which occurs due to heating from internal gravitational collapse. Jupiter's smaller size leaves its center too cool to ignite, sustaining instead internal masses of liquefied gas.

For more information, please visit Nine Planets: Jupiter