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Jupiter reigns supreme among the planets, containing two-thirds of the planetary mass of the solar system.

Saturn, the sixth planet from the Sun, is one of the five planets visible from Earth without a telescope.

An obscuring haze gives Uranus a bland, velvety appearance. In 1986 Voyager 2 confirmed that Uranus possesses a system of at least 11 thin, widely separated rings.

Astronomers discovered Neptune as a result of their efforts to understand the orbit of Uranus. Neptune orbits the Sun every 165 years, and is the smallest of the solar systems gas giants.

We've put together some great images of the gas giants FREE for you to download.

WHAT ARE THE GAS GIANTS?

Jupiter is the largest of the four "jovian planets" or "gas giants" grouped with Saturn, Uranus, and Neptune.
Great globes of dense gas, with little or no rocky material, they formed in cooler parts of our solar system's protosolar cloud, so gases and ices were preserved. These planets take from almost 12 years to almost 165 years to circle the Sun, but they spin on their axes remarkably rapidly, in 10 to 16 hours, rather than in days or months.
The giant planets are virtually all atmosphere. On Jupiter and Saturn, we see spectacular banded patterns of swirling, brilliantly colored clouds. At high altitudes, the clouds probably are composed of frozen ammonia crystals; in effect, there is a high layer of ammonia clouds like the high-altitude cirrus clouds of Earth. At lower altitudes Jupiter's clouds are probably made of water and complex molecules. The atmospheres of far-off Uranus and Neptune are hard to study, but show faint traces of clouds as well.

We can only make informed conjectures about the interiors of the gas giants. They may have small rocky cores; if so, the cores are surrounded by layers of solid ice. Around this ice, in Jupiter and Saturn, the enormous pressure of the overlying material has reduced the molecular hydrogen gas (which makes up most of the atmosphere) to a liquid state in which the hydrogen behaves electrically like a metal. In Uranus and Neptune, the hydrogen is dense but may not reach the
metallic condition. Currents circulating in the metallic fluids of Jupiter and Saturn generate powerful magnetic fields that surround the two planets in space and trap atomic particles from the "solar wind" that streams outward from the Sun.
The gas giants have solid moons orbiting around them. Not just one or two moons, like Earth and Mars, but whole families; Jupiter and Saturn have more than a dozen moons apiece.
Their moons, recently photographed by the Voyagers 1 and 2 spacecraft, have been revealed as an astonishing collection of distinct individuals: large irregular rocks, worlds of cratered ice, and one moon of incessant glowing volcanic eruptions. The largest of Saturn's moons, Titan, is covered by a dense brownish atmosphere of nitrogen and methane, with minor amounts of other organic molecules.
Within each of the two planetary groups - the terrestrial planets and the gas giants - our space probes have revealed tremendous diversity. Each world is unique, but each also has something in common with the others, so that by studying one, it is possible to discover basic truths that relate to them all.