Jupiter, also known as the Giant Among Giants for its massive size, is the fourth outermost planet in our Solar System. It joins Neptune, Uranus, and Saturn as one of the giant planets. Giant planets are unimaginably huge, stunningly beautiful, and sometimes a little weird. They are made mostly of gases instead of solid materials.
The largest planets in our solar system, Saturn and Jupiter are made up mostly of hydrogen and helium. They rotate fast and have strong winds and storms. Because they are so massive, temperatures and pressures deep within them increase to extraordinary levels. Hydrogen takes on a liquid metallic form. The nature of their rocky cores remains a mystery.
Jupiter is wider than 11 Earths. It has more mass than all the other seven planets of our solar system combined.
Jupiter’s Great Red Spot is a gigantic storm that has been observed for over three centuries. More than 10,000 miles (16,000 kilometers) across, it rotates counterclockwise.
Jupiter’s colorful cloud bands spin around the planet at different speeds. The dark dot on the bottom left of this image is the shadow of the moon Europa on Jupiter’s ammonia clouds.
All four giant planets have rings. Jupiter, Uranus, and Neptune have only a few faint, narrow rings that are difficult to observe.
Voyager 2 was the spacecraft that made the surprising discovery that Jupiter had rings. They are so thin and faint that they had never been seen from Earth.
The innermost ring, known as the halo, consists of dust particles that rise above and below the ring plane. The main ring is flat. Two thin structures called the gossamer rings lie outside.
Jupiter has 79 moons. The Voyager spacecraft revealed the moons of the giant planets to be surprisingly diverse worlds in their own right. Further exploration has unveiled intricate surfaces both young and old, volcanoes and impact features, huge plumes and geysers, deep canyons, subsurface oceans, and even clues to possible environments that might be friendly to simple forms of life.
The moons of Jupiter and Saturn are not dead, unchanging worlds. Several show evidence of geologic activity throughout their history. Complex patterns, faulting, cliffs, and deep canyons tell stories of stresses and resurfacing that have shaped and reshaped the terrain. Explore some of Jupiter's moons in the gallery below.