Satellite systems, giant planets

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. 

Ice mantles are important constituents of interstellar grains in molecular clouds, and icy bodies dominate the outer reaches of the solar system. The region of the solar system where ices were stable increased with time as the solar system formed, as accretion rates of materials to the disk waned and the disk cooled. The giant planets and their satellites formed, in part, from these ices, and probably also from the nebular gas itself. 

It includes chapters on the origin of the elements and solar system abundances, the solar nebula and planet fomiution. meteorite classitlcation. the major types of meteorites, important processes in early solar system history, geochemistry of the terrestrial planets, the giant planets and their satellites, comets, and the formation and early differentiation of the Earth. This volume is intended to be the first reference work one would consult to learn about the chemistry of the solar system. 

It is thought to be highly probable that gas hydrates exist elsewhere in the solar system and beyond, wherever the right conditions prevail, e.g., in the gaseous giant planets and on many of their moons. The crust of the Jovian satellite Europa probably contains ciathrate hydrates in abundance,and it was postulated that CO2 hydrate exists on Mars. 

The outer or giant planets - Jupiter. Saturn, Uranus, and Neptune - are massive low-density bodies with a rocky core surrounded by deep layers consisting mainly of solid, liquid, and gaseous hydrogen and helium. They are much further from the sun and therefore much cooler. All have large numbers of satellites Jupiter has at least 63 Saturn at least 61 Uranus 27 and Neptune 13. The outer planets also have ring systems composed of smaller bodies, rocks, dust, and ice particles. 

Asteroids, comets and smaller particles are also grouped into SSSBs, small solar system bodies. All categories of objects described above appear at specific locations in the solar system. The inner solar system contains the terrestrial planets and the Main Belt of asteroids. In the middle region there are the giant planets with their satellites and the centaurs. The outer solar system comprises the Trans-Neptunian objects including the Kuiper Belt, the Oort cloud, and the vast region in between. 

Water is one of the basic elements for life. It is even assumed that the evolution of life is only possible if there is liquid water present. A water molecule has some remarkable properties that make it quite unique in the universe. In the first chapter of this book we will review these basic properties of water and the role of water on Earth. All ancient civilizations realized the importance of water and their cities were constructed near great reservoirs of water. But is water unique on Earth Do we find water elsewhere in the solar system, on extrasolar planetary systems or in distant galaxies We will start the search for the presence of extraterrestrial water in our solar system. Surprisingly enough it seems that water in some form and sometimes in only minute quantities is found on any object in the solar system. Even on the planet nearest to the Sun, Mercury, there may be some water in the form of ice near its poles where never the light of Sun heats the surface. And there are objects in the solar system that are made up of a large quantity of water in terms of their mass, like comets and several satellites of the giant planets. 

The term "Solar System ice" denotes in general a solidified volatile and/or mixtures of solidified volatiles. The Solar System ices are mostly water ice H2O, but also solidified CO2, CO, NH3, N2, SO2, CH4 and many other simple molecules as well as the organics. On the surfaces of many of the satellites of the giant planets (Jupiter, Saturn, Uranus, and Neptune) water ice is the dominant component. Therefore, in the following we will adopt the common assumption that a satellite is composed of water ice, and silicates. The radii and the masses of all satellites but the smallest ones are well known. Therefore their densities are known as well, see Table 1. Taking into account that the densities of water ice are about 940,1190, and 1360 kg m at phases I, II, and VI, respectively, and that the density of the silicates is (3400 400) kg m" the mass ratio C of silicates to total mass of the satellite can be estimated. This is rather simple for large satellites however, the estimate can fail for smaller satellites because of the possible bulk primordial porosity left fi-om an epoch of formation. 

Among places where condensates accreted into significant solid bodies, such as planets, habitable realms have always been rarer than places that were either too cold or too hot for life to exist. Much of our Solar System s mass is still far too hot for life. Most of the deep interiors of the gas giants and rocky planets are too hot, as is, of course, the Sun itself. Most of the surface area of solid bodies in the Solar System are too cold - the icy satellites of the outer planets and the myriad comets and Kuiper Belt Objects on the far outer fringes of the Solar System. In this sense, places like the surfaces of Earth and Mars and Europa s subsurface ocean are indeed very rare places. 

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