Jupiter, Saturn, Uranus and Neptune, the fourth, fifth, sixth and seventh, the outside or the planets farthermost from the sun are referred to as the Jovian planets. They are the coldest, the iciest, and by far less well known.
The Jovian planets are composed of helium and hydrogen mainly, are much large than the earth and their gravity is stronger. They have many moons, and they all orbit the sun with axial positions, have lower temperatures since the distance from the sun is greater than that of the interstellar planets, the first four planets, Mercury, Venus, Earth and Mars.
*Jupiter, the fifth planet from the sun, is the largest non stellar planet - non stellar meaning not among the stars visible from earth - being 318 times larger in mass than planet earth, and volume wise, is 1,400 greater. In fact, one on-line writer to this planet as "a gas giant." What they mean is that gas encircles the interior and no actual divisions between the different substances are known to exist.
Jupiter wields a heavy hand - wand - among its neighbors, and how it acts influences the actions of other planets. The Kirkwood gap in the atmosphere is blamed on this huge gas ball. Basically these are low density areas in the asteroid belt discovered in 1860 by David Kirkwood.
*Saturn, the sixth planet from the sun nine and a half times larger than the earth. It's rings are brilliant and this is its most distinguishing mark. Although there are other Jovian planets have rings, they are not as illustrious, and are often hard to see. In comparison with other more leaden and solid planets, Mercury as an example, Saturn is lightweight. As is noted in Random History, if "Saturn is the least dense planet in the solar system, and if there were a body of water large enough to hold Saturn, the planet would float. In contrast, Earth and Mercury would sink the fastest."
Saturn has been orbited by explorers. The first was the Cassini-Huygens spacecraft July, 1, 2004. The journey began around years earlier on October 15, 1997 and flying at 70,700 miles an hour it made the 2,000,000,000 mile trip. It is still in progress and will end in 2012, a little less than two years from now, February, 11, 2011. Pioneer 11, flew past this planet in 1979, having started six year earlier in 1973, and likewise in 1980 and 1981 Voyagers 1 and 2 took a look by flying past. What do astronomers think if Saturn? They call it the Jewel of the solar system because of its bright and shiny rings that glow.
Saturn was discovered William Herschel in 1789 and he was fascinated by the rings which he called handles. Now three hundred plus years later telescopes are more powerful and more detailing can be seen, although Saturn is so brilliant it can be seen by the naked eye from earth. In fact it is nicknamed the naked eye planet.
*Uranus is the seventh planet from the sun, the third of the Jovian four, and was also discovered by William Herschel in 1781, eight years before he discovered Saturn. It is seen as blue because of the absorption of the red light caused by methane. It has a rocky interior as well as gas and ice.
An interesting feature about Uranus is its fifteen moons that have been named after Shakespearean characters. Why? As homage. In " Midsummer's Night's Dream he had one of his characters say, "I thank thee for thy sunny beams; I thank thee, Moon, for shining now so bright." Oberon, Titania, Ariel, Umbriel, Miranda, Juliet, Puck, Cordelia, Ophelia, Bianca, Desdemona, Rosalind, Cressida, and Belinda.
The astronomers opened the gates to the heavenly bodies, and in appreciation for William Shakespeare having so honored the moon many centuries ago, these witty adventurers found a way make earth and sky friendlier, and far less daunting for researchers. Ariel now its your turn to show Puck a thing or two.
*Neptune, the eight and the last planet, now that Pluto has been downgraded, was named for the God of water in Roman mythology. It has no solid surface and is not well known. An attempt to learn more, Voyager 2 got close enough to discoverer winds of 700 miles per second, the fastest winds known of any of the planets. Although Neptune gets less sun than any of the other planets, it is hot. A temperature of around 353 (214 C) and this suggests on the inside there must be lots activity. Adding to that thought, the four rings encircling Neptune are made up mainly of dust particles.
Although wonderful discoveries are being made about the planets, there are still unknowns. Most of the planets are not conducive to being explored by neighboring earth creatures, and much of what is written is possibly semi-factual. Yet what's the harm in wondering if there might not be life elsewhere up there. It happened on earth, why not on Mars, or one of the other planets? Unfortunately, our Creator may be telling us, everything in its time. First clean up earth and then take another look up there in the outer universe. You may like what you see.