Jupiter/Saturn

Alkanes have the general molecular- formula C H2 +2- The simplest one, methane (CH4), is also the most abundant. Large fflnounts are present in our atmosphere, in the ground, and in the oceans. Methane has been found on Jupiter, Saturn, Uranus, Neptune, and Pluto, and even on Halley s Comet. 

Our solar system consists of the Sun, the planets and their moon satellites, asteroids (small planets), comets, and meteorites. The planets are generally divided into two categories Earth-like (terrestrial) planets—Mercury, Venus, Earth, and Mars and Giant planets—Jupiter, Saturn, Uranus, and Neptune. Little is known about Pluto, the most remote planet from Earth. 

The gas giant planets Jupiter, Saturn, Uranus and Neptune. The planet Pluto has a status of its own, and has recently been renamed a dwarf planet. 

Elements Venus Earth Mars Jupiter Saturn... 

The density estimates in Table 7.1 show a distinction between the structures of the planets, with Mercury, Venus, Earth and Mars all having mean densities consistent with a rocky internal structure. The Earth-like nature of their composition, orbital periods and distance from the Sun enable these to be classified as the terrestrial planets. Jupiter, Saturn and Uranus have very low densities and are simple gas giants, perhaps with a very small rocky core. Neptune and Pluto clearly contain more dense materials, perhaps a mixture of gas, rock and ice. 

Alkanes are often found in natural systems. They are the main constituents in the atmospheres of the planets Jupiter, Saturn, Uranus, and Neptune. Methane is also thought to have been a major component of the atmosphere of the early Earth. Natural gas and oil are primarily made of alkanes. 

Aspects of the chemical composition of the atmospheres of Jupiter, Saturn, Uranus, and Neptune were measured by the Voyager and Galileo spacecraft in the 1980s and 1990s,... 

Hydrogen isotopic compositions, expressed as molar D/H ratios, of solar system bodies. The relatively low D/H values in the atmospheres of Jupiter and Saturn are similar to those in the early Sun, whereas D/H ratios for Uranus and Neptune are intermediate between the Jupiter-Saturn values and those of comets and chondrites. The Earth s oceans have D/H shown by the horizontal line. Mars values are from SNC meteorites. Modified from Righter et al. (2006) and Lunine (2004). 

Several applications of IR spectroscopy to astrophysics have been made. Small amounts of methane in the earth s atmosphere have been detected by the observation of weak IR absorption lines in solar radiation that has passed through the earth s atmosphere. Intense IR absorption bands of CH4 have been found in the spectra of the atmospheres of Jupiter, Saturn, Uranus, and Neptune. Bands of ammonia have been observed for Jupiter and Saturn bands of C02 have been observed in the Venusian spectrum and bands of H20 have been observed in the Martian spectrum. 

When thinking about how our solar system may have evolved from proplyds (protoplanetary disks), we must remember that the violence of the early Solar System was tremendous as huge chunks of matter bombarded each other. In the inner Solar System, the Sun s heat drove away the lighter-weight elements and materials, leaving Mercury, Venus, Earth, and Mars behind. In the outer part of the system, the solar nebulas (gas and dust) survived for some time and were accumulated by Jupiter, Saturn, Uranus, and Neptune. 

But what was there, in addition to water, on the primitive Earth The four outer planets of the solar system (Jupiter, Saturn, Uranus and Neptune) are still made up mainly of hydrogen, helium, methane, ammonia and water, and it is likely that those same chemicals were abundant everywhere else in the solar system, and therefore even in its four inner planets (Mercury, Venus, Earth and Mars). These were too small to trap light chemicals, such as hydrogen and helium, but the Earth had a large enough mass to keep all the others. It is likely therefore that the Earth s first atmosphere had great amounts of methane (CH4), ammonia (NHJ and water, and was, as a result, heavy and reducing, like Jupiter s. 

The chemical dynamics, reactivity, and stability of carbon-centered radicals play an important role in understanding the formation of polycyclic aromatic hydrocarbons (PAHs), their hydrogen-dehcient precursor molecules, and carbonaceous nanostructures from the bottom up in extreme environments. These range from high-temperature combustion flames (up to a few 1000 K) and chemical vapor deposition of diamonds to more exotic, extraterrestrial settings such as low-temperature (30-200 K), hydrocarbon-rich atmospheres of planets and their moons such as Jupiter, Saturn, Uranus, Neptune, Pluto, and Titan, as well as cold molecular clouds holding temperatures as low as 10... 

Constituents Jupiter Saturn Uranus Neptune CJ4,0 (15%) Terrestrial Planets Mg, Si, Fe (0.25%)... 

Studies of the reactions of many atmospherically important atomic and free radical species were described in Section 9 this Section deals primarily with important molecular species. A brief review of the progress achieved recently in the field of atmospheric chemistry has been provided by Cox, " with emphasis on the reactions of O3 and important H-, N-, C-, halogen-, and S-containing species. Waynehas reviewed extraterrestrial atmospheric photochemistry and Strobel " has reviewed the photochemistries of the atmospheres of Jupiter, Saturn, and Titan. Kaye and Strobeldescribed a 1-dimensional photochemical model of PHj chemistry in the atmosphere of Saturn. A study of the photochemical reactions of H2O and CO in the Earth s primitive atmosphere has been presented by Bar-Nun and Chang. " They concluded that even if the primitive atmosphere initially contained no H2 and contained carbon only in the form of CO and CO2, photochemical processes would have enriched the environment with a variety of organic compounds. 

Thommes E. W., Duncan M. J., and Levison H. F. (1999) The formation of Uranus and Neptune in the Jupiter-Saturn region of the solar system. Nature 402, 635-638. 

Modern telescopic and spacecraft study of Jupiter, Saturn, Uranus, and Neptune, their properties, and their systems of rings, moons, and magnetospheres, has been the purview of the planetary scientist with little connection to the universe beyond until 1995, when the first extrasolar giant planet was discovered. Now the solar system s giants are the best-studied example of a class of some 100 objects which—while only one has been measured for size and hence density—may be present 10% of Sun-like stars. 

Neptune is the eighth planet from the Sun and about four times the size of Earth. Astronomers consider Neptune to form with Uranus a subgroup of the Jovian planets (Jupiter, Saturn, Uranus, and Neptune). Neptune and Uranus are similar in size, mass, periods of their rotation, the overall features of their magnetic fields, and ring systems. However they differ in the structure of their atmospheres (perhaps the more conspicuous features of Neptune s clouds are caused by its significant internal energy source, which Uranus lacks), the orientations of their rotation axes, and in their satellite systems. 

Neptune s upper atmosphere (what we see) is a mixture of hydrogen, helinm, methane and traces of acetylene (C2H2), carbon dioxide, and other gasses. Orrly 10% of the planet s mass is in this outermost layer (approximately 3,100 mi or 5,000 km thick). Under the upper atmophere lies a lower atmophere of molecnlar (gaseous) hydrogen and helium, plus some ices (approximately 6,200 mi or 10,000 km thick). Below the atmosphere lies the mantle, a water ice and rock mixture that perhaps contains methane ice and aitrmonia ice mixed in. A core is at the center of the planet s mass, and it is likely a body with a 6,200-mi radios and represents 45% of the planet s mass that is conposed of silicate rock and water ice. Like the other Jovian planets (Jupiter, Saturn, and Uranns), Neptune has a distinctive structure quite different from the terrestrial planets like Earth. 

Solid N2, CH4, H2O, and CO have been found on Triton and Pluto, witli additional CO2 on Triton. The molecule N2 dominates both surfaces, and other molecules are trapped in an N2 matrix. The only molecule identified on Charon is H2O. Surface compositions of these two bodies are quite different from those of satellites of Jupiter, Saturn, and Uranus. The compositional relationsliip of Triton and Pluto to that of tlie Edgeworth-Kuiper belt objects, and to tlie comets, is still unclear. 

At the time, more than a dozen planetary satellites had already been discovered for Jupiter, Saturn, Uranus, and Neptune. None had been found for Venus or Mercury, nor were they likely to be found, given the proximity of these planets to the Sun. Mars likewise had no satellites. .. or, at least, none that had yet been discovered. 

The solar system is sometimes divided into two parts consisting of the inner planets—Mercury, Venus, Earth, and Mars—and the outer planets—Jupiter, Saturn, Uranus, Neptune, and, until recently, Pluto. One might imagine that understanding the chemical and physical properties of the inner planets would help in understanding the chemical and physical properties of the outer planets. No such luck. The two groups of planets differ from each other in some fundamental and important ways. 

Voyager 2 was launched at an especially propitious moment in the history of the solar system At the time four of the outer planets— Jupiter, Saturn, Uranus, and Neptune—were aligned in such a way as to allow the spacecraft to fly past them all, providing scientists with their first close look at the next-to-outermost planets, Uranus and Neptune, in addition to the planned targets of Jupiter and Saturn. The alignment that permitted this special tour of observation occurs only once every 175 years, so the data provided by Voyager 2 about Uranus and Neptune has been of very special value to researchers. 

The bar is a unit for measuring pressure, equal to the pressure exerted by Earth s atmosphere at sea level. The bar is commonly used to express positions within the atmosphere of Jupiter, Saturn, and some other planets. Low values, such as 0.1 bar, represent upper regions of the atmosphere, while high values, such as 100 bar, represent lower regions. The higher the bar value for a measurement, the deeper the level of the atmosphere represented.)... 

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