The Solar System Home | Site Map | What's New | Image Index | Copyright | Posters | ScienceViews | Science Fiction Timelines | The Solar System For I dipped into the Future, far as human eye could see; saw the vision of the world, and all the wonder that would be. -Alfred Lord Tennyson, 1842 Table of Contents Multiwavelength Milky Way Our solar system consists of an average star we call the Sun , the planets Mercury , Venus , Earth , Mars , Jupiter , Saturn , Uranus , Neptune , and Pluto . It includes: the satellites of the planets; numerous comets , asteroids , and meteoroids; and the interplanetary medium. The Sun is the richest source of electromagnetic energy (mostly in the form of heat and light) in the solar system. The Sun's nearest known stellar neighbor is a red dwarf star called Proxima Centauri, at a distance of 4.3 light years away. The whole solar system, together with the local stars visible on a clear night, orbits the center of our home galaxy, a spiral disk of 200 billion stars we call the Milky Way . The Milky Way has two small galaxies orbiting it nearby, which are visible from the southern hemisphere.

They are called the Large Magellanic Cloud and the Small Magellanic Cloud. The nearest large galaxy is the Andromeda Galaxy . It is a spiral galaxy like the Milky Way but is 4 times as massive and is 2 million light years away. Our galaxy, one of billions of galaxies known, is traveling through intergalactic space. The planets, most of the satellites of the planets and the asteroids revolve around the Sun in the same direction, in nearly circular orbits. When looking down from above the Sun's north pole, the planets orbit in a counter-clockwise direction. The planets orbit the Sun in or near the same plane, called the ecliptic . Pluto is a special case in that its orbit is the most highly inclined (18 degrees) and the most highly elliptical of all the planets. Because of this, for part of its orbit, Pluto is closer to the Sun than is Neptune . The axis of rotation for most of the planets is nearly perpendicular to the ecliptic. The exceptions are Uranus and Pluto , which are tipped on their sides. Composition Of The Solar System The Sun contains 99.85% of all the matter in the Solar System.

The planets, which condensed out of the same disk of material that formed the Sun, contain only 0.135% of the mass of the solar system. Jupiter contains more than twice the matter of all the other planets combined. Satellites of the planets, comets, asteroids, meteoroids, and the interplanetary medium constitute the remaining 0.015%. The following table is a list of the mass distribution within our Solar System. Sun: 99.85% Interplanetary Space Nearly all the solar system by volume appears to be an empty void. Far from being nothingness, this vacuum of "space" comprises the interplanetary medium. It includes various forms of energy and at least two material components: interplanetary dust and interplanetary gas. Interplanetary dust consists of microscopic solid particles. Interplanetary gas is a tenuous flow of gas and charged particles, mostly protons and electrons -- plasma -- which stream from the Sun , called the solar wind . The solar wind can be measured by spacecraft, and it has a large effect on comet tails. It also has a measurable effect on the motion of spacecraft.

The speed of the solar wind is about 400 kilometers (250 miles) per second in the vicinity of Earth's orbit. The point at which the solar wind meets the interstellar medium, which is the "solar" wind from other stars, is called the heliopause. It is a boundary theorized to be roughly circular or teardrop-shaped, marking the edge of the Sun's influence perhaps 100 AU from the Sun. The space within the boundary of the heliopause, containing the Sun and solar system, is referred to as the heliosphere. The solar magnetic field extends outward into interplanetary space; it can be measured on Earth and by spacecraft. The solar magnetic field is the dominating magnetic field throughout the interplanetary regions of the solar system, except in the immediate environment of planets which have their own magnetic fields. The Terrestrial Planets The terrestrial planets are the four innermost planets in the solar system, Mercury , Venus , Earth and Mars . They are called terrestrial because they have a compact, rocky surface like the Earth's. The planets, Venus, Earth, and Mars have significant atmospheres while Mercury has almost none. The following diagram shows the approximate distance of the terrestrial planets to the Sun.

The Jovian Planets Jupiter , Saturn , Uranus , and Neptune are known as the Jovian (Jupiter-like) planets, because they are all gigantic compared with Earth, and they have a gaseous nature like Jupiter's. The Jovian planets are also referred to as the gas giants, although some or all of them might have small solid cores. The following diagram shows the approximate distance of the Jovian planets to the Sun. Our Milkyway Galaxy This image of our galaxy, the Milky Way, was taken with NASA's Cosmic Background Explorer's (COBE) Diffuse Infrared Background Experiment (DIRBE). This never-before-seen view shows the Milky Way from an edge-on perspective with the galactic north pole at the top, the south pole at the bottom and the galactic center at the center. The picture combines images obtained at several near-infrared wavelengths. Stars within our galaxy are the dominant source of light at these wavelengths. Even though our solar system is part of the Milky Way, the view looks distant because most of the light comes from the population of stars that are closer to the galactic center than our own Sun.

(Courtesy NASA) Our Milky Way Gets a Makeover Like early explorers mapping the continents of our globe, astronomers are busy charting the spiral structure of our galaxy, the Milky Way. Using infrared images from NASA's Spitzer Space Telescope, scientists have discovered that the Milky Way's elegant spiral structure is dominated by just two arms wrapping off the ends of a central bar of stars. Previously, our galaxy was thought to possess four major arms. This artist's concept illustrates the new view of the Milky Way, along with other findings presented at the 212th American Astronomical Society meeting in St. Louis, Mo. The galaxy's two major arms (Scutum-Centaurus and Perseus) can be seen attached to the ends of a thick central bar, while the two now-demoted minor arms (Norma and Sagittarius) are less distinct and located between the major arms. The major arms consist of the highest densities of both young and old stars; the minor arms are primarily filled with gas and pockets of star-forming activity. The artist's concept also includes a new spiral arm, called the "Far-3 kiloparsec arm," discovered via a radio-telescope survey of gas in the Milky Way.

This arm is shorter than the two major arms and lies along the bar of the galaxy. Our sun lies near a small, partial arm called the Orion Arm, or Orion Spur, located between the Sagittarius and Perseus arms. (Courtesy NASA/JPL-Caltech) Spiral Galaxy, NGC 4414 The majestic galaxy, NGC 4414, is located 60 million light-years away. Like the Milky Way, NGC 4414 is a giant spiral-shaped disk of stars, with a bulbous central hub of older yellow and red stars. The outer spiral arms are considerably bluer due to ongoing formation of young, blue stars, the brightest of which can be seen individually at the high resolution provided by the Hubble camera. The arms are also very rich in clouds of interstellar dust, seen as dark patches and streaks silhouetted against the starlight. (Courtesy NASA/STSCI) Obliquity of the Eight Planets This illustration shows the obliquity of the eight planets. Obliquity is the angle between a planet's equatorial plane and its orbital plane.

By International Astronomical Union (IAU) convention, a planet's north pole lies above the ecliptic plane. By this convention, Venus, Uranus, and Pluto have a retrograde rotation, or a rotation that is in the opposite direction from the other planets. (Copyright 2008 by Calvin J. Hamilton) The Solar System During the past three decades a myriad of space explorers have escaped the confines of planet Earth and have set out to discover our planetary neighbors. This picture shows the Sun and all nine planets of the solar system as seen by the space explorers. Starting at the top-left corner is the Sun followed by the planets Mercury , Venus , Earth , Mars , Jupiter , Saturn , Uranus , Neptune , and Pluto . (Copyright 1998 by Calvin J. Hamilton) The Largest Moons and Smallest Planets This image shows the relative sizes of the largest moons and the smallest planets in the solarsystem.

The largest satellites pictured in this image are: Ganymede (5262 km), Titan (5150 km), Callisto (4806 km), Io (3642 km), the Moon (3476 km), Europa (3138 km), Triton (2706 km), and Titania (1580 km). Both Ganymede and Titan are larger than planet Mercury followed by Io, the Moon, Europa, and Triton which are larger than the planet Pluto . (Copyright Calvin J. Hamilton) Diagram of Portrait Frames On February 14, 1990, the cameras of Voyager 1 pointed back toward the Sun and took a series of pictures of the Sun and the planets, making the first ever "portrait" of our solar system as seen from the outside. This image is a diagram of how the frames for the solar system portrait were taken. (Courtesy NASA/JPL) All Frames from the Family Portrait This image shows the series of pictures of the Sun and the planets taken on February 14, 1990, for the solar system family portrait as seen from the outside.

In the course of taking this mosaic consisting of a total of 60 frames, Voyager 1 made several images of the inner solar system from a distance of approximately 6.4 billion kilometers (4 billion miles) and about 32° above the ecliptic plane. Thirty-nine wide angle frames link together six of the planets of our solar system in this mosaic. Outermost Neptune is 30 times further from the Sun than Earth . Our Sun is seen as the bright object in the center of the circle of frames. The insets show the planets magnified many times. (Courtesy NASA/JPL) Portrait of the Solar System These six narrow-angle color images were made from the first ever "portrait" of the solar system taken by Voyager 1 , which was more than 6.4 billion kilometers (4 billion miles) from Earth and about 32° above the ecliptic . Mercury is too close to the Sun to be seen. Mars was not detectable by the Voyager cameras due to scattered sunlight in the optics, and Pluto was not included in the mosaic because of its small size and distance from the Sun.

These blown-up images, left to right and top to bottom are Venus , Earth , Jupiter , Saturn , Uranus , and Neptune . (Courtesy NASA/JPL) The following table lists statistical information for the Sun and planets: Distance Jovian Planets The Jovian Planets This section is relatively short because .... well, .. we really don't know very much about the giant, gaseous planets that inhabit the outer regions of our solar system. The probes and orbiters we sent to these worlds have sent back volumes of data which only tend to raise more questions than provide concrete answers. Relative sizes of the Jovian planets As stated in the introduction, all the Jovian planet have rings (Saturn being the most pronounced) and each planet has a family of moons. We know the rings are composed of much smaller ice particles whirling around these planets, some as small as the size of dust. Astronomers have often wondered how these two features are related. For example, are the rings a permanent feature on each planet? Did the moons form from the rings? Do incoming asteroids and comets, on occasion, smash into a moon, ... blasting it into smaller pieces which later becomes raw material for the rings?

Did a comet get too close to the planet, and the tidal forces pulled it to pieces, ... providing raw material for making rings? Lots of questions, ... no definitive answers! Jupiter Credit NASA Jupiter is, by far, the most massive of all the planets (and it is the largest). It has a mass 318 times that of the earth. It has (like all the Jovian planets), a low density. The reason comes from the fact that it is composed of lighter gasses which are very similar to the composition of the sun, 90% hydrogen and 10% helium (at least at the "surface"). Why the quotes? Because Jupiter shows no solid surface (although astronomers believe a solid body exists deep below the gasses). When we look at Jupiter, we see a chaotic, swirling, turbulent, thick atmosphere. Jupiter is mainly a giant gas planet. The pressure of this hydrogen gas becomes so high as you move down through the atmosphere that it behaves more like a liquid than a gas, so maybe we should call Jupiter a liquid hydrogen planet. Jupiter has a very strong magnetic field (20,000 time stronger than the earth's magnetic field).

This suggests that Jupiter has a fairly active interior. Perhaps the swirling liquid hydrogen acts as a huge dynamo to create this effect. Jupiter also radiates much more energy into space than it receives from the sun. This excess energy may come from one or all of the suggestions below: heat released by the radioactive decay of elements? heat produced by some chemical reactions? heat produced by a nuclear reactions in the center? Jupiter is collapsing and heating up the gasses? Heat is still escaping from the time it was formed? The Great Red Spot The upper layers of the Jovian atmosphere show distinct light and dark bands of turbulent gasses. The exact reason why these bands appear in the first place is still unknown. The planet only takes about 10 hours to rotate once on its axis but because it is a gas planet, the region near the equator rotates slightly faster than the gasses do at higher latitudes. It has been suggested that these bands represent areas where gasses are rising and sinking in the atmosphere. In other words, a complex system of convection cells where clouds of ammonia are exposed from lower layers. Within one of the bands in the southern region, exists a great "storm" which has raged for over 300 years.

It is known as the "great red spot". Apparently, storms on Jupiter last a long time. The moons of Jupiter Probably the most interesting features of Jupiter are moons which orbit the planet. Over 60 moons have already been found around Jupiter, but the spotlight remains on the four Galilean moons - Io, Europa, Ganymede, and Callisto. Io Callisto Credit NASA (Click on each for a closer look) Io has the most dynamic surface known in the solar system. This "pizza moon" orbits quite close to Jupiter where tidal forces become extremely high. This generates a lot of internal heat as Io is constantly being re-shaped. The results is the most active volcanic surface known. Every day, the surface is reformed as sulfur erupts from the interior. Europa has an icy surface covered by cracks. Astronomers believe that an ocean of liquid water may exist below the ice. As tidal forces generate internal heat, and stress on the ice, ... it cracks ... and liquid water from below moves to the surface and freezes. Wow! Some day we will have to land on this moon to see if it could harbor life. Ganymede is the largest of all the moons in the solar system.

It is even larger than Mercury (or Pluto), but since it orbits Jupiter, its status is reduced to a simple satellite. Callisto is the least active of the Galilean satellites. It has many more crater impacts than the others listed, which tell us it probably has a much older surface. Saturn Credit NASA Jupiter and Saturn are actually quite similar to each other. Saturn, of course, has a much more spectacular systems of rings than Jupiter and a lower density too. The density of Saturn is so low, it could float on water. This is probably because Saturn has a smaller solid part (buried deep under the gasses) or much less hydrogen in the liquid state (or both). We will learn much more about this system when we receive data from the Cassini probe which has already reached Saturn on July 2004. Perhaps the most interesting features of Saturn are the beautiful system of rings and one of its many moons - Titan. Rings of Saturn As stated before, the rings are just smaller pieces of debris which orbit Saturn on a flat plane. The rings are, in fact, incredibly flat, ... having a thickness of a few tens of meters (about the height of a typical tree).

The individual pieces are most likely water ice but also solid fragments. They range from the size of a small building to the size of a dust particle. Italian astronomer, Giovanni Domenico Cassini (1625-1712), noticed gaps in the rings, which are still known as Cassini divisions. Astronomers still don't have a complete understanding regarding these divisions, but they must involve a complex gravitational interaction between the individual ring particles and the moons which orbit within the rings. Even magnetic forces from Saturn are most likely involved in forming this complex structure. Astronomers have a long way to go. The moon - Titan Titan from Voyager 2 Credit NASA Titan from Cassini -credit VIMS Team, U. Arizona, ESA, NASA Titan is the largest moon of Saturn and also the most unusual. It, like Ganymede, is larger than Mercury (or Pluto). Titan captured the imagination of early astronomers ever since they discovered that it had an atmosphere. Even stranger, spectral analysis shows that Titan's atmosphere is a "smog" of methane, ethane, and carbon dioxide. We had to go there!!!! On 2005 the Cassini craft released the Huygens probe, ...

which landed on Titan in January 2005. It showed us ravines carved out by liquid hydrocarbons. It rains methane on Titan! The moon - Enceladus The Cassini probe made a pretty interesting discovery in 2005. As it flew past the small moon Enceladus, it observed ice geysers shooting from the moon's south pole region. This gives astronomers yet another place to wonder if a liquid ocean lies below the ice. Could life exist there too? Uranus and Neptune Uranus and Neptune Credit NASA These two middleweight gas planets lie far from the sun. They are also mostly hydrogen and helium in composition but appear blue because of small amounts of atmospheric methane which absorbs most of the spectrum and reflects blue light. Uranus is unusual in that its axis is tilted 98 degree to the plane of the ecliptic, giving it the most extreme "seasons" of any planet. It basically spins on its side. Neptune is one of the windiest planets, with speeds up to 700 mph. This discovery was a big surprise since it was felt that atmospheric activity would be slower in deep cold space.

Apparently, Neptune's atmosphere is driven by internal heat rather than heat from the sun. Miranda Surface of Miranda Credit NASA (click on image to enlarge) One of the moons of Uranus is quite usual. Miranda's surface looks like a random mixture of rock and ice. This suggests that this moon was recently re-assembled. That is, it may be that some moons form when ring material coalesces under the force of gravity. Does this mean that rings may be a temporary "phase" in the evolution of a planet? Astronomers caution that it can happen only if tidal forces (exerted by the planet) can be overcome. For example, the rings of Saturn will not form into a moon because the rings lie within the planet's "Roche limit". That is, they lie too close to Saturn ... so close that tidal forces will disrupt any attempt to assemble them into a larger body. It still may be that the rings of Saturn are a temporary feature, but they will not become a moon. Exploring the Kuiper Belt We will just have to be patient. The New Horizons spacecraft is scheduled to reach Pluto in July 2015.

It might be interesting to know that the largest moon of Pluto - Charon, is large enough to consider the system a "double object" Not only was Pluto demoted to a dwarf planet, it now has to share the stage with a partner. As of 2014, there are 5 known satellites associated with Pluto. Pluto isn't even the king of the hill in the Kuiper belt. Eris is more massive (and slightly larger) than Pluto. Poor Pluto. Making a solar system ... or just when you thought you understood it ... something happens Astronomers believed that they knew how our solar system was formed and why it has the overall properties we find in our solar system today. Our sun, they believed, formed from a great cloud of gas, known as the solar nebula. As the gasses within the nebula condensed and contracted, they eventually formed the sun. However, a small amount of material was left behind which formed a disk of debris (known as an accretion disk). This orbiting material would become the raw material for making the planets. This part of the story is even backed up by photographs of other stellar systems. Credit C. Burrows and J.

Krist (STScI), WFPC2 IDT Team, NASA, ESA Beta Pictoris We now know that many young stars have an flat accretion disk of debris surrounding them. This could be solar systems in the making. Astronomers believed that solid planetesimals quickly collect together to make the planets. The inner planets are small and dense because it is far too hot for icy (lower density) planetesimals to form in that region. Farther from the sun (where it is much colder), planetesimals of rock and ice are able to form. This means the Jovian planets are able to grow much bigger and more massive. Eventually, they acquire so much mass that they are able to gravitationally attract the much lighter gasses such as hydrogen and helium. Bingo ... you just made a giant gas world. The problem is ... astronomers have since discovered many star systems with planets ... but they don't look anything like our solar system. These systems (which now number well over 1000 in 2014) show giant gassy planets which orbit very close to their parent star. It is like finding a "super Jupiter" lying inside the orbit of Mercury ....

hence the name "hot Jupiters". Astronomers didn't think this was possible, so the model needs revision. Is it possible that these planets formed in a more distant sector of their solar system and then migrated closer to the parent star? Another question is ... is our solar system "typical" or a planetary "freak"? It is too early to answer these questions. Rouge Planets (Orphan Planets) Things got fuzzier with the discovery of rouge planets . These are planets drifting in space and not associated with any parent star. The origin of these orphans is puzzling. Did they form around a star and get ejected? Did they form in open space all by themselves? How many rouge planets are there? Could one of these planets get "captured" by an approaching star? More questions than answers! Another Earth? The list of exoplanets keeps growing. The hunt to find "Earth's twin" is under way.. The goal of the Kepler observatory (and future Transiting Exoplanet Survey Satellite or TESS, scheduled for launch in 2017) may succeed in finding another world like our home planet. Several close matches have been confirmed.

I plan on making this question a topic for class discussion so I will resist posting any results. When our planetary brother is found, will it orbit in the "habitable zone" (making liquid water possible)? Will we discover life ... intelligent life? This is a very exciting time in astronomy! ï¿½Jim Mihal 2004, 2014- all rights reserved What are the Jovian Planets? - Universe Today Universe Today What are the Jovian Planets? Article Updated: 6 Jul , 2016 by Matt Williams Beyond our Solar System’s “ Frost Line ” – the region where volatiles like water, ammonia and methane begin to freeze – four massive planets reside. Though these planets – Jupiter, Saturn, Uranus and Neptune – vary in terms of size, mass, and composition, they all share certain characteristics that cause them to differ greatly from the terrestrial planets located in the inner Solar System. Officially designated as gas (and/or ice) giants, these worlds also go by the name of “Jovian planets”. Used interchangeably with terms like gas giant and giant planet, the name describes worlds that are essentially “Jupiter-like”.

And while the Solar System contains four such planets, extra-solar surveys have discovered hundreds of Jovian planets, and that’s just so far… Definition: The term Jovian is derived from Jupiter, the largest of the Outer Planets and the first to be observed using a telescope – by Galileo Galilei in 1610 . Taking its name from the Roman king of the gods – Jupiter, or Jove – the adjective Jovian has come to mean anything associated with Jupiter; and by extension, a Jupiter-like planet. The giant planets of the Solar System (aka. the Jovians). Credit: spiff.rit.edu Within the Solar System, four Jovian planets exist – Jupiter, Saturn, Uranus and Neptune. A planet designated as Jovian is hence a gas giant, composed primarily of hydrogen and helium gas with varying degrees of heavier elements. In addition to having large systems of moons, these planets each have their own ring systems as well. Another common feature of gas giants is their lack of a surface, at least when compared to terrestrial planets.

In all cases, scientists define the “surface” of a gas giant (for the sake of defining temperatures and air pressure) as being the region where the atmospheric pressure exceeds one bar (the pressure found on Earth at sea level). Structure and Composition: In all cases, the gas giants of our Solar System are composed primarily of hydrogen and helium with the remainder being taken up by heavier elements. These elements correspond to a structure that is differentiated between an outer layer of molecular hydrogen and helium that surrounds a layer of liquid (or metallic) hydrogen or volatile elements, and a probable molten core with a rocky composition. Due to difference in their structure and composition, the four gas giants are often differentiated, with Jupiter and Saturn being classified as “gas giants” while Uranus and Neptune are “ice giants”. This is due to the fact that Neptune and Uranus have higher concentrations of methane and heavier elements – like oxygen, carbon, nitrogen, and sulfur – in their interior. Interior models of the giant planets, showing rocky cores overlaid by solid and gaseous envelopes. Credit: NASA/JPL In stark contrast to the terrestrial planets, the density of the gas giants is slightly greater than that of water (1 g/cm³).

The one exception to this is Saturn, where the mean density is actually lower than water (0.687 g/cm3). In all cases, temperature and pressure increase dramatically the closer one ventures into the core. Atmospheric Conditions: Much like their structures and compositions, the atmospheres and weather patterns of the four gas/ice giants are quite similar. The primary difference is that the atmospheres get progressively cooler the farther away they are from Sun. As a result, each Jovian planet has distinct cloud layers who’s altitudes are determined by their temperatures, such that the gases can condense into liquid and solid states. In short, since Saturn is colder than Jupiter at any particular altitude, its cloud layers occur deeper within it’s atmosphere. Uranus and Neptune, due to their even lower temperatures, are able to hold condensed methane in their very cold tropospheres, whereas Jupiter and Saturn cannot. The presence of this methane is what gives Uranus and Neptune their hazy blue color, where Jupiter is orange-white in appearance due to the intermingling of hydrogen (which gives off a red appearance), while the upwelling of phosphorus, sulfur, and hydrocarbons yield spotted patches areas and ammonia crystals create white bands.

Jupiter and Saturn have similar appearances, owing to their similar compositions and atmospheres. Credit: NASA/GSFC The atmosphere of Jupiter is classified into four layers based on increasing altitude: the troposphere, stratosphere, thermosphere and exosphere. Temperature and pressure increase with depth, which leads to rising convection cells emerging that carry with them the phosphorus, sulfur, and hydrocarbons that interact with UV radiation to give the upper atmosphere its spotted appearance. Saturn’s atmosphere is similar in composition to Jupiter’s. Hence why it is similarly colored, though its bands are much fainter and are much wider near the equator (resulting in a pale gold color). As with Jupiter’s cloud layers, they are divided into the upper and lower layers, which vary in composition based on depth and pressure. Both planets also have clouds composed of ammonia crystals in their upper atmospheres, with a possible thin layer of water clouds underlying them. Uranus’ atmosphere can be divided into three sections – the innermost stratosphere, the troposphere, and the outer thermosphere. The troposphere is the densest layer, and also happens to be the coldest in the solar system .

Within the troposphere are layers of clouds, with methane clouds on top, ammonium hydrosulfide clouds, ammonia and hydrogen sulfide clouds, and water clouds at the lowest pressures. Next is the stratosphere, which contains ethane smog, acetylene and methane, and these hazes help warm this layer of the atmosphere. Here, temperatures increase considerably, largely due to solar radiation. The outermost layer (the thermosphere and corona) has a uniform temperature of 800-850 (577 °C/1,070 °F), though scientists are unsure as to the reason. Uranus and Neptune, the Solar System’s ice giant planets. Credit: Wikipedia Commons This is something that Uranus shares with Neptune, which also experiences unusually high temperatures in its thermosphere (about 750 K (476.85 °C/890 °F). Like Uranus, Neptune is too far from the Sun for this heat to be generated through the absorption of ultraviolet radiation, which means another heating mechanism is involved. Neptune’s atmosphere is also predominantly hydrogen and helium, with a small amount of methane.

The presence of methane is part of what gives Neptune its blue hue, although Neptune’s is darker and more vivid. Its atmosphere can be subdivided into two main regions: the lower troposphere (where temperatures decrease with altitude), and the stratosphere (where temperatures increase with altitude). The lower stratosphere is believed to contain hydrocarbons like ethane and ethyne, which are the result of methane interacting with UV radiation, thus producing Neptune’s atmospheric haze. The stratosphere is also home to trace amounts of carbon monoxide and hydrogen cyanide, which are responsible for Neptune’s stratosphere being warmer than that of Uranus. Weather Patterns: Like Earth, Jupiter experiences auroras near its northern and southern poles. But on Jupiter, the auroral activity is much more intense and rarely ever stops. These are the result of Jupiter’s intense radiation, it’s magnetic field, and the abundance of material from Io’s volcanoes that react with Jupiter’s ionosphere. Reprocessed view by Bjorn Jonsson of the Great Red Spot taken by Voyager 1 in 1979 reveals an incredible wealth of detail. Credit: NASA/JPL Jupiter also experiences violent weather patterns .

Wind speeds of 100 m/s (360 km/h) are common in zonal jets, and can reach as high as 620 kph (385 mph). Storms form within hours and can become thousands of km in diameter overnight. One storm, the Great Red Spot , has been raging since at least the late 1600s. The storm has been shrinking and expanding throughout its history; but in 2012, it was suggested that the Giant Red Spot might eventually disappear . Jupiter also periodically experiences flashes of lightning in its atmosphere , which can be up to a thousand times as powerful as those observed here on the Earth. Saturn’s atmosphere is similar, exhibiting long-lived ovals now and then that can be several thousands of kilometers wide. A good example is the Great White Spot (aka. Great White Oval), a unique but short-lived phenomenon that occurs once every 30 Earth years. Since 2010, a large band of white clouds called the Northern Electrostatic Disturbance have been observed enveloping Saturn, and is believed to be followed by another in 2020.

The winds on Saturn are the second fastest among the Solar System’s planets, which have reached a measured high of 500 m/s (1800 km/h). Saturn’s northern and southern poles have also shown evidence of stormy weather. At the north pole, this takes the form of a persisting hexagonal wave pattern measuring about 13,800 km (8,600 mi) and rotating with a period of 10h 39m 24s. Saturn makes a beautifully striped ornament in this natural-color image, showing its north polar hexagon and central vortex. Credit: NASA/JPL-Caltech/Space Science Institute The south pole vortex apparently takes the form of a jet stream, but not a hexagonal standing wave. These storms are estimated to be generating winds of 550 km/h, are comparable in size to Earth, and believed to have been going on for billions of years. In 2006, the Cassini space probe observed a hurricane-like storm that had a clearly defined eye. Such storms had not been observed on any planet other than Earth – even on Jupiter.

Uranus’s weather follows a similar pattern where systems are broken up into bands that rotate around the planet, which are driven by internal heat rising to the upper atmosphere. Winds on Uranus can reach up to 900 km/h (560 mph), creating massive storms like the one spotted by the Hubble Space Telescope in 2012. Similar to Jupiter’s Great Red Spot, this “ Dark Spot ” was a giant cloud vortex that measured 1,700 kilometers by 3,000 kilometers (1,100 miles by 1,900 miles). Because Neptune is not a solid body, its atmosphere undergoes differential rotation, with its wide equatorial zone rotating slower than the planet’s magnetic field (18 hours vs. 16.1 hours). By contrast, the reverse is true for the polar regions where the rotation period is 12 hours. This differential rotation is the most pronounced of any planet in the Solar System, and results in strong latitudinal wind shear and violent storms. Reconstruction of Voyager 2 images showing the Great Dar Spot (top left), Scooter (middle), and the Small Dark Spot (lower right).

Credit: NASA/JPL The first to be spotted was a massive anticyclonic storm measuring 13,000 x 6,600 km and resembling the Great Red Spot of Jupiter. Known as the Great Dark Spot , this storm was not spotted five later (Nov. 2nd, 1994) when the Hubble Space Telescope looked for it. Instead, a new storm that was very similar in appearance was found in the planet’s northern hemisphere, suggesting that these storms have a shorter life span than Jupiter’s. Exoplanets: Due to the limitations imposed by our current methods, most of the exoplanets discovered so far by surveys like the Kepler space observatory have been comparable in size to the giant planets of the Solar System. Because these large planets are inferred to share more in common with Jupiter than with the other giant planets, the term “Jovian Planet” has been used by many to describe them. Many of these planets, being greater in mass than Jupiter, have also been dubbed as “Super-Jupiters” by astronomers. Such planets exist at the borderline between planets and brown dwarf stars , the smallest stars known to exist in our Universe.

They can be up to 80 times more massive than Jupiter but are still comparable in size, since their stronger gravity compresses the material into an ever denser, more compact sphere. Artist’s concept of the “Hot Jupiter” exoplanet HD 149026b. Credit: NASA/JPL-Caltech Those Super-Jupiters that have distant orbits from their parent stars are known as “Cold Jupiters”, whereas those that have close orbits are called “Hot Jupiters”. A surprising number of Hot Jupiters have been observed by exoplanet surveys, due to the fact that they are particularly easy to spot using the Radial Velocity method – which measures the oscillation of parent stars due to the influence of their planets. In the past, astronomers believed that Jupiter-like planets could only form in the outer reaches of a star system. However, the recent discovery of many Jupiter-sized planets orbiting close to their stars has cast doubt on this. Thanks to the discovery of Jovians beyond our Solar System, astronomers may be forced to rethink our models of planetary formation. Since Galileo first observed Jupiter through his telescope, Jovian planets have been an endless source of fascination for us.

And despite many centuries of research and progress, there are still many things we don’t know about them. Our latest effort to explore Jupiter, the Juno Mission , is expected to produce some rather interesting finds. Here’s hoping they bring us one step closer to understanding those darn Jovians! For more information, check out NASA’s Solar System Exploration page and Science Daily’s the Jovian planets . Astronomy Cast has a number of episodes on the Jovian planets, including Episode 56: Jupiter . Share this: NOVA | Teachers | Origins: Where are the Aliens? | Research Reading: Terrestrial and Jovian Planets | PBS Origins: Where Are the Aliens? Research Reading Terrestrial and Jovian Planets With the exception of Pluto, planets in our solar system are classified as either terrestrial (Earth-like) or Jovian (Jupiter-like) planets. Terrestrial planets include Mercury, Venus, Earth, and Mars. These planets are relatively small in size and in mass. A terrestrial planet has a solid rocky surface, with metals deep in its interior. In the solar system, these planets are closer to the sun and are therefore warmer than the planets located farther out in the solar system.

Future space missions are being designed to search remotely for terrestrial planets around other stars. The layers of gases surrounding the surface of a planet make up what is known as an atmosphere. The atmospheres of the terrestrial planets range from thin to thick. Mercury has almost no atmosphere. A thick atmosphere made mostly of carbon dioxide covers Venus, trapping heat and raising surface temperatures. Clouds on Venus form from sulfuric acid. Earth's atmosphere is 77 percent nitrogen, 21 percent oxygen, and 1 percent argon, with variable amounts of water vapor, and trace amounts of other gases. White clouds of water vapor hide much of Earth's surface in views of Earth from space. Mars has a very thin atmosphere containing mostly carbon dioxide, with nitrogen, argon, and trace amounts of oxygen and water vapor. The atmosphere also contains thin water and carbon dioxide clouds, and is frequently affected by dust storms. Jovian planets include Jupiter, Saturn, Uranus, and Neptune. These planets have larger sizes and masses. Jovian planets do not have solid surfaces. They are sometimes called gas giants because they are large and made mostly of gases. Small amounts of rocky materials are only found deep in the cores of Jovian planets.

In the solar system, Jovian planets are located farther from the sun than terrestrial planets, and are therefore cooler. Scientists have found more than 100 Jovian planets around other stars. The majority of the extrasolar Jovian planets that have been discovered so far are closer to their stars than the Jovian planets in the solar system are to the sun. The atmospheres of the Jovian planets in our solar system are made mostly of hydrogen and helium. Compounds containing hydrogen, such as water, ammonia, and methane, are also present. Differences in the amounts of these trace gases and variations in the temperatures of these planets contribute to the different colors seen in images taken in visible light. While scientists expect the atmospheres of Jovian planets in other solar systems to be composed mainly of hydrogen and helium, they have not yet measured the properties of their atmospheres. Pluto, the most remote planet in our solar system, might be little more than a giant comet. Pluto resembles the icy, comet-like objects orbiting the Sun outside of Neptune's orbit, rather than either the rocky terrestrial planets or the Jovian planets.

Factors that distinguish Pluto from the terrestrial and Jovian planets include its composition (ice, rock, and frozen gases), changing atmosphere, small size, comparatively large moon, and its elliptical orbit around the Sun. © WGBH Educational Foundation Terrestrial and Jovian Planets Essay Terrestrial and Jovian Planets Terrestrial and Jovian Planets Our solar system contains nine planets, which are broken down into 2 classifications known as terrestrial planets and jovian planets. The terrestrial planets are composed primarily of rock and metal. They also generally have high densities, slow rotation, solid surfaces, no rings, and few satellites. These planets include Mercury, Venus, Earth, and Mars. On the other hand, the jovian planets are composed primarily of hydrogen and helium. They generally have low densities, rapid rotation, deep atmospheres, rings, and numerous satellites. These planets include Jupiter, Saturn, Uranus, and Neptune. The closest terrestrial planet to the sun is Mercury. Mercury is relatively small, and technically the eighth largest of all the planets. It is actually smaller in diameter than the moons Ganymede and Titan. Mercury has been visited by only one spacecraft, and that was the Mariner 10.

The temperature variations on Mercury are the most extreme of any in the solar system. Temperatures range from 90K to 700K. Venus is slightly hotter, but much more stable. Mercury is in many ways similar to the moon. The biggest comparison is the surface being heavily cratered and very old. Mercury is also the second densest planet in the solar system, only behind earth. Mercury actually has a very thin atmosphere consisting of atoms blown off the planet by solar winds. Mercury is often visible with binoculars, and sometimes even the naked eye. The best place to find Mercury is always near the Sun. The next terrestrial planet, and second planet from the sun, is Venus. Venus is the brightest object in the sky except for the Sun and the Moon. The first spacecraft to visit the planet was the Mariner 2 in 1962. It has also been visited by many other spacecrafts, including the Pioneer Venus, Venera 7, Venera 9, and most recently the US spacecraft Magellan. The rotation on Venus is somewhat unusual because it is very slow and also retrograde. One day on Venus is equivalent to 243 days on Earth.

The atmosphere on Venus is composed almost entirely of Carbon Dioxide. It contains several layers of clouds made up of sulfuric acid. These clouds completely cover up our view of the planet. The dense atmosphere produces a greenhouse effect that raises the temperatures to nearly 400 degrees, which is 740K. Venus' surface is actually hotter than Mercury's, despite being nearly twice as far from the Sun. There are also very strong winds on the planet that reach up to 350 kph. Venus is usually visible to the naked eye. Being the brightest star in the sky makes Venus easily seen on starry nights. The next terrestrial planet, and third planet from the Sun, is our Earth. Earth is the only planet whose English name does not derive from Greek or Roman mythology. Earth is the densest major body in the solar system. Unlike the other terrestrial planets, Earth is divided into solid plates that float around independently on top of the hot mantle. There are eight major plates and twenty or so smaller plates. Seventy-one percent of the Earth is made of water. Earth happens to be the only planet on which water can exist as a liquid form on the surface.

The Earth's atmosphere is 77% nitrogen, 21% oxygen, and has traces of argon, carbon dioxide, and water. Earth is the only planet with human life, and as a result, this is planet is our home. The last terrestrial planet, and fourth planet from the Sun, is Mars. Mars is a fairly small planet, and as a result is the seventh largest of all the planets. Mars is commonly referred to as the Red Planet, due to its red color. The first spacecraft to visit Mars was the Mariner 4 in 1965. Several others closely followed including the Mariner 2, Viking, and Mars Pathfinder. Mars has a very thin atmosphere composed of 95.3% carbon dioxide, 2.7% nitrogen, and 1.6% argon. Mars thin atmosphere also produces a greenhouse effect, however it only raises the temperature slightly. When it is nighttime, Mars is easily visible to the unaided eye. The fifth planet from the Sun, and first of the jovian planets, is Jupiter. Jupiter is by far the largest of all the planets. Jupiter is more than twice as big as all the other planets combined.

Jupiter happens to be the fourth brightest planet in the sky, only behind the Sun, Moon, and Venus. Jupiter was first visited by the Pioneer 10 in 1973. Jupiter is the first of the gaseous, and therefore does not have a solid surface. However, the gaseous material gets more and more dense with depth. Jupiter is made up of 90% hydrogen, and 10% helium. Jupiter is also home of the Great Red Spot. The Great Red Spot is a high pressure region whose clouds are higher and colder than the surrounding regions. How I spent my vacation on Mercury There are eight planets in our solar system, which is called the Milky Way. The eight planets in 1,310 Words | 6 Pages Planet of the Apes When Planet of the Apes opened in theaters, few people knew what to expect. To most, the idea of a movie 1,058 Words | 5 Pages A Comparison of the Planets in the Sol System Shaun J.

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Question: Jovian relates to which planet in our solar system?
Answer: Jupiter