The Jovian Planets

Come experince our solar system's unknown mysteries

Join us on this marvelous journey through the planets of the outer solar system. While the terrestrial planets are quite bizarre worlds to us, you'll find that the further we travel through our solar system, the less we know about our neighboring planets


Named after the king of the Roman gods, our first stop will be Jupiter. At 741 million kilometers from the sun, Jupiter is the largest planet in our solar system. Jupiter's diameter is 11 times that of Earth, but it's density is only 1/4 of Earth's. Jupiter is slightly flattened at the poles. Jupiter is composed primarily of gaseous and liquid matter. Jupiter is thought to consist of a dense core with a mixture of elements, a surrounding layer of liquid metallic hydrogen with some helium, and an outer layer predominantly of molecular hydrogen.Beyond this basic outline, there is still considerable uncertainty. The core is often described as rocky, but its detailed composition is unknown, as are the properties of materials at the temperatures and pressures of those depths. The core region is surrounded by dense metallic hydrogen, which extends outward to about 78% of the radius of the planet.Rain-like droplets of helium and neon precipitate downward through this layer, depleting the abundance of these elements in the upper atmosphere.
Jupiter takes nearly 12 years to circle the sun, although it spins counter clockwise on its axis once every 9 hours and 55 minutes. Jupiter's atmosphere consists of about 90% hydrogen and 10% helium, with small amounts of methane, ammonia, and water vapor. Jupiter is perpetually covered with clouds composed of ammonia crystals and possibly ammonium hydrosulfide. The clouds are located in the tropopause and are arranged into bands of different latitudes, known as tropical regions. These are sub-divided into lighter-hued zones and darker belts. The interactions of these conflicting circulation patterns cause storms and turbulence. Wind speeds of 100 m/s . The cloud layer is only about 50 kilometers deep, and consists of at least two decks of clouds: a thick lower deck and a thin clearer region. There may also be a thin layer of water clouds underlying the ammonia layer. The colors seen in Jupiter's upper atmosphere are though to be the result of chemical reactions induced by sunlight and/or by lightning in the atmosphere. However, this is still an open question. Because Jupiter is considered a gas planet, its atmosphere is then considered its surface. Jupiter does have a surface but it is not solid and there is still not a term scientists have assigned to it. Jupiter's natural satellites include its roughly 64 moons divided into three categories: fragmented moonlets, the four Galilean satellites, and the remaining 56 which orbit in a clockwise direction, opposite from the rest of Jupiter's moons. Jupiter's rings are known to be made of tiny particles, extending 0.8 planetary radius from the planet's surface. The rings are thought to be continually replenished, likely from meteoroid impacts on small moonlets within or near it.


Named after the Roman god of capitol, wealth, agriculture, liberation, and time, our next stop takes us to Saturn, 1.4 billion kilometers from the sun. Saturn's diameter is 120,000 kilometers and has density half of Jupiter's. It takes Saturn 29.5 years to orbit the sun, and it rotates counter clockwise on its axis once every 10 hours and 40 minutes. Saturn's atmosphere is comprised of about 96% hydrogen and 3% helium, with only about 1% of heavier materials, about the same as the composition of the sun. Saturn has cloud bands in its atmosphere, but they’re pale orange and faded. This orange color is because Saturn has more sulfur in its atmosphere. In addition to the sulfur in Saturn’s upper atmosphere, there are also quantities of nitrogen and oxygen. Saturn has some of the fastest winds in the Solar System, some going as fast as 1800 km/hour at the planet’s equator. Large white storms can form within the bands that circle the planet, but unlike Jupiter, these storms only last a few months and are absorbed into the atmosphere again. The part of Saturn that was can see is the visible cloud deck. The clouds are made of ammonia, and sit about 100 km below the top of Saturn’s troposphere. Below this upper cloud deck is a lower cloud deck made of ammonium hydrosulphide clouds, located about 170 km below. The lowest cloud deck is made of water clouds, and located about 130 km below the troposphere. Although it has a surface, it is not as solid as other planets. Saturn’s surface is so dense that the gravity on it is particularly very weak and is only 91% compared to that of Earth’s. It will not allow anyone to take a stroll on the planet. The pressure is very high that not only will freezing temperatures turn objects into solid ice but the high level of pressure will crush objects before it hits the surface. Saturn's natural satellites includes its 62 moons, most of which consist of dirty ice such as we see on some of Jupiter's moons. Each of Saturn's moons is unique, most consisting of leftover pieces of the disintegration of pre-existing moons as a result of powerful collisions. Saturn's rings are made up of small particles of water and ice mixed with smaller amounts of rocky and organic matter. Particles nearer to the planet move faster than those farther out. While we originally thought Saturn only had three rings, we know now that there are many more. Small moons, called shepherd moons, orbit near the rings, causing the rings to keep their shape. While various hypothesis have been used to explain the various features of the rings, no comprehensive theory has yet to be proposed.


Named after the Roman god of the sky, our third destination takes us 2.88 billion kilometers from the sun to Uranus. With a diameter of 51,000 kilometers, Uranus density had been calculated to be 1.27 times that of water. Since we discovered that Uranus can subject materials to pressure 2 million times that of Earth's atmosphere, it may be that Uranus has a very small rocky core or no core at all. Like Venus, Uranus orbits clockwise once every 84 years around the Sun. However, it still rotates counterclockwise on its axis once every 17 hours and 14 minutes. Like Jupiter and Saturn, Uranus's atmosphere also consists mostly of hydrogen and helium, with some methane. The absorption of red light by the methane reflecting the rest on the spectrum gives Uranus its blue color. Uranus is so gaseous that it doesn't really have a surface. As such, the surface of Uranus is one of the most fascinating things that one can study. In fact, it's so unique that its atmosphere is actually its surface. The giant gaseous planet has no solid surface and what we've learned is that the surface is composed of fluids. The whole make up of Uranus being a giant planet is its gases. Uranus is actually a massive heavenly body made up of ice and gas. Its center which is icy will freeze objects that pass through its atmosphere before reaching the surface Unlike Jupiter and Saturn, Uranus does not have any cloud layers. Uranus' natural satellites includes it 27 moons. Since Uranus' rings only reflect about 5% of the sunlight that hits them, they are not visible from Earth . The rings are made of a dark material, as dark as soot. To date, there are 13 rings to Uranus.

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Named after the Roman god of the seas, our final destination brings us 4.5 billion kilometers from the sun to Neptune. Neptune's size and composition matches that of Uranus, and it's blue colors are result of the same cause. However, since light penetrates deeper into Neptune, it is a more deep blue than Uranus. One feature of the planet Neptune is its Great Dark Spot. The Great Dark Spot is actually a depression in Neptune's atmosphere that is surrounded by high cirrus type of clouds. However, this spot does not have stability in its appearance. Neptune orbits counterclockwise around the sun once every 164.79 years, and rotates counterclockwise on its axis once every 16.11 hours. There are two main layers that compose Neptune's s atmosphere: the troposphere and the stratosphere. In the troposphere the temperature decreases as the altitude increases. The opposite is true for the stratosphere. The temperature increases as the altitude increases. The area which separates the two is known as the tropopause.

Neptune’s troposphere is composed of clouds that differ in composition based on the ranging altitude. Methane clouds fill the upper-level of Neptune. Presuures between 1-5 bars allow ammonia and hydrogen sulfide clouds to form. If the pressure is more than 5 bars, ammonium sulfide, hydrogen sulfide and water clouds may form. Clouds of water-ice may form at 50 bars of pressure. The lower stratosphere of Neptune is foggy because of the condensation of acetylene and ethane. There are also small amounts of hydrogen cyanide and carbon monoxide present in Neptune. The thermosphere of Neptune has a very high temperature, around 750 K. Scientists haven’t figured out where the heat generates from as Neptune is very far from the Sun. Many theories have been suggested and have yet to be proven. Neptune's natural satellites consists of its 13 moons. These moons are classified as Regular Moons and Irregular Moons. Regular moons are closer to the planet, some even closer than Neptune’s planetary rings. Irregular moons orbit farther from Neptune. Neptune's rings are faint and dense. Even the densest of the five rings of Neptune pale in comparison to the less dense rings of Saturn. It is comparable to Jupiter’s rings that are mostly made of dust particles. These five rings were discovered by the Voyager 2 in 1989 and have been studied by astronomers ever since.

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Heading Home

After our tour of Neptune, we will return back to our own planet. The Jovian planets certainly are different from the worlds of the inner solar system . Compared to the terrestrial planets, the Jovians are larger, more massive, more fluid, less dense, and rotate faster. Their moon are different from on others. Although we see great similarities between them, we also see great differences. Each is an individual world with its own history.