Solar system orbital evolution

Cosmochemislry places important constraints on models for the origin of the solar nebula and the formation and evolution of planets. We explore nebula constraints by defining the thermal conditions under which meteorite components formed and examine the isotopic evidence for interaction of the nebula with the ISM and a nearby supernova. We consider how planetary bulk compositions are estimated and how they are used to understand the formation of the terrestrial and giant planets from nebular materials. We review the differentiation of planets, focusing especially on the Earth. We also consider how orbital and collisional evolution has redistributed materials formed in different thermal and compositional regimes within the solar system. 

Orbital and collisional evolution of the modern solar system... 

No description of our sofar system s formation wouid be complete without a discussion of the profound changes wrought by its orbital and collisional evolution. Although these physical processes may not seem to be related to cosmochemistry, they have changed the spatial distribution of planets and small bodies of differing compositions within the solar system, and in some cases, even the bulk compositions of large bodies. Understanding these processes can help us appreciate how some of the cosmochemical conundrums and complexities of the solar system arose. 

The geochemistry of the natural satellites of the outer solar system provides important clues and constraints on the formation of the planets about which they orbit, the formation and nature of the satellites themselves, and the various processes that have shaped their histories and evolution. Historically, little was known about the geochemical... 

As accurately as these calculations can be made, however, the behavior of celestial bodies over long periods of time cannot always be determined. For example, the perturbation method has so far been unable to determine the stability either of the orbits of individual bodies or of the solar system as a whole for the estimated age of the solar system. Studies of the evolution of the Earth-Moon system indicate that the Moon s orbit may become unstable, which will make it possible for the Moon to escape into an independent orbit around the Sun. Recent astronomers have also used the theory of chaos to explain irregular orbits. 

Planetology and astrogeology are separate branches of science that examine the physical and chemical characteristics of the planets and minor bodies in the solar system. The principle difference between these two scientific disciplines is that planetology is inclusive of all planetary bodies, while astrogeology concentrates on those worlds that are basically similar to the Earth. Scientists within the field of planetology can study a variety of topics that include planetary atmospheres, interiors, orbital characteristics, the potential for life, and all aspects of planetary formation and evolution. In comparison, astrogeology essentially concentrates on the various surface features and geological processes of the Earth as seen on other worlds. 

The question of the origin and evolution of the solar system is one of the most fundamental in astronomy. It bears directly on such related issues as stellar evolution, the formation of planetary systems, and on the existence of life itself. Gamma-ray observations from spacecraft, either via remote sensing from orbit or through in situ measurements... 

In 1930, Tombaugh discovered Pluto, the outermost known planet (Reaves, 1997 Marcialis, 1997). Several authors have derived the radius of Pluto with very small uncertainties unfortunately, the derived values do not overlap. Consequently, only a broad range can be quoted (1145 to 1200 km) within which the true radius of Pluto may fall (Tholen Buie, 1997). Pluto is by far the smallest planet of our Solar System it is even smaller than many planetary satellites. Pluto s orbit is highly eccentric and inclined by more than 17° to the ecliptic plane (Malhotra Williams, 1997). At perihelion (29.7 AU), Pluto is closer to the Sun than Neptune (30.1 AU), and at aphelion it reaches a heliocentric distance of almost 50 AU. Pluto s orbital period, 248.35 sidereal years, is locked in a 3 2 ratio with that of Neptune (Cohen Hubbard, 1965). The axis of rotation is nearly in the orbital plane therefore, this small planet undergoes rather complex seasonal changes (Spencer et al., 1997). Malhotra (1993, 1999) provides interesting discussions of the possible evolution of Pluto s orbit and that of other planets (see also Stem etai, 1997). 

Collisions between comets and planets have occurred often during the evolution of the solar system. Cometary impacts on early Earth may have deposited a substantial amount of water to the Earth. The masses of lost and retained water after the impacts of comets and asteroids on oceans of various depths were studied by Svetsov, 2009 [330], The bombardment of an atmosphereless planet by fast asteroids can wipe out the most part of an ocean. Because of their mass loss during perihelion passage, it is difficult to predict cometary orbits with high precision. Therefore an impact of a comet on a planet cannot be predicted precisely. 

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