Abstract: A three-parameter method for modeling the position and shape of planetary bow waves was chosen to model the near portion of the Venus, earth and Mars bow shocks, and its results were compared with those of models using one to six free variables. It was found that the relative effective shapes of the near Martian, Cytherean, and terrestrial bow shocks are ellipsoidal, paraboloidal, and hyperboloidal, respectively, in response to the increasing bluntness of the obstacles that the planets present to the solar wind. No significant deviations from axial symmetry were found when the near bow waves of the earth and Venus were mapped into the aberrated terminator plane, in agreement with gas dynamic theory predictions neglecting the effects of the IMF because of their minuteness.

Abstract: Various investigations concerning Jupiter, Uranus and Saturn are discussed. Revisions in the Galilean satellite ephemerides led to a new interpretation of earth-based measurements of Jovian oblateness which agrees with Pioneer measurements. In the area of scintillation theory, a semi-qualitative result was obtained for spike profiles produced by finite stellar disks viewed through Kolmogorov turbulence. It was also possible to set limits on the systematic distortion of stellar occulation profiles by turbulence which minimize the systematic distortion problem. The position of Miranda was studied for the purpose of obtaining an accurate prediction of a possible stellar occultation by Miranda in 1977, following an occultation of the same star by Uranus. In addition, using thermodynamic calculations, a model was developed for the adiabiatic cooling of Jovian-type planets and an observational test of the model was proposed. The dynamic structure of Saturn's rings was also studied.

Abstract: High resolution Voyager IRIS measurements for Saturn and Jupiter are assembled in meridional cross sections of the retrieved upper tropospheric temperatures. The calculated thermal wind shear in the upper troposphere is highly correlated on both planets with the cloud top winds derived from imaging data. In contrast, temperatures below approximately 300 mbar are not simply related to the zonal jet structure. The upper tropospheric temperatures seem to have been more consistently correlated with cloud top winds than with major albedo features at the time of the Voyager encounters.

Abstract: Exploration of space in recent years has highlighted the importance of impact cratering as a geological proces operating on terestrial planetary bodies. This review outlines some aspects of the process and summarizes the key observational data available on impact cratering. It ilustrates how the preserved cratering histories of the planets can provide important information on the nature and evolution of planetary surfaces.

Abstract: Recent research results concerning the atmospheres of the outer planets and satellites are presented, covering Pluto, Triton, Neptune, Uranus, Titan, Saturn, and Io. In addition to presenting analyses of physical properties and atmospheric chemical composition, attention is given to (1) the origin of Pluto; (2) the possible variability of Triton; (3) the rotation periods of Uranus and Neptune, as well as their effective temperatures and internal heating, haze distribution, thermal structure, and weather and seasonal changes; (4) the seasonal and long-term changes of Titan, in addition to its thermal structure; (5) the dust and haze distribution of Saturn; and (6) Io's gaseous plasma and neutral torio. The data include Voyager 1 and 2 results for Io, along with Pioneer 11 results for Saturn and Titan.

Abstract: Abundances of primordial noble gases are lower for Mars than for Earth, but are higher for Venus The data for Venus are attributed to implantation of solar wind in small preplanetary particles Results for Mars are explained by escape of gas from planetesimals with radius between 5 and 100 km which form within the first 107 yr of the Solar System Volatile loss is associated with melting caused by short-lived radioisotopes such as 26Al

Abstract: The golden age of solar system exploration, N.W.Hinners the sun, R.W Noyes magnetospheres, cosmic rays and the interplanetary medium, J.A.Van Allen the moon, P.D.Spudis Mars, M.H.Carr planet Earth, D.L.Anderson surfaces of the terrestrial planets, J.W.Head, III atmospheres of the terrestrial planets, J.B.Pollack the Voyager encounters, B.A.Smith interiors of the giant planets, W.B.Hubbard atmospheres of the giant planets, A.P.Ingersoll planetary rings, J.A.Burns the Galilean satellites, T.V.Johnson Titan, T.Owen icy bodies of the outer solar system, D.P.Cruikshank and D.Morrison the Halley encounters, R.Reinhars comets, J.C.Brandt asteroids, C.R.Chapman meteorites, J.A.Wood small bodies and their origins, W.K.Hartmann the collision of solid bodies, E.W.Shoemaker and C.S.Shoemaker life in the new solar system?, G.A.Soffen putting it all together, J.S.Lewis.

Abstract: Competing models seek to describe the sun's two giant companions. In one model the winds are confined to a thin layer at the surface; in another the winds extend through the fluid depths of each planet.

Abstract: The ultraviolet spectra of Uranus, Neptune, and Titan do not reveal absorption features at 7-A resolution from 2100 to 3200 A. Upper limits of from 1 to 3 A are set for the equivalent widths of narrow absorptions, which corresponds to a CO/H2 mixing ratio less than 2 x 10 to the -4th in the case of Uranus. The slopes of the continuum reflectivities of Uranus and Neptune are consistent with the semi-infinite Rayleigh-Raman scattering model of Cochran, while the absolute levels are matched only if solar photometry is modified within acceptable limits. An alternative, but less satisfactory explanation of the new data is that the UV reflectivities of both Uranus and Neptune are depressed uniformly by a continuum absorber. The suggestion by Savage et al (1980) that the albedo of Uranus decreases by approximately 20% from 2200 to 1800 A is not confirmed. For Titan, the albedo decreases monotonically toward shorter wavelengths down to 2300 A. New limits are set for the pressure level in the atmosphere of Titan up to which the real, but presently unidentified, UV absorber there must extend, and for the fraction of Titan that must be covered by this absorber

Abstract: Radio science experiments use radio links between spacecraft and sensor instrumentation that is implemented in the Deep Space Network The deep space communication complexes along with the telecommunications subsystem on board the spacecraft constitute the major elements of the radio science instrumentation Investigators examine small changes in the phase and/or amplitude of the radio signal propagating from a spacecraft to study the atmospheric and ionospheric structure of planets and satellites, planetary gravitational fields, shapes, masses, planetary rings, ephemerides of planets, solar corona, magnetic fields, cometary comae, and such aspects of the theory of general relativity as gravitational waves and gravitational redshift

Abstract: If you really want to be smarter, reading can be one of the lots ways to evoke and realize. Many people who like reading will have more knowledge and experiences. Reading can be a way to gain information from economics, politics, science, fiction, literature, religion, and many others. As one of the part of book categories, planets and satellites always becomes the most wanted book. Many people are absolutely searching for this book. It means that many love to read this kind of book.

Abstract: Comparisons of earth and Venus topography by use of Pioneer/Venus radar altimetry are examined. Approximately 93% of the Venus surface has been mapped with a horizontal resolution of 200 km and a vertical resolution of 200 m. Tectonic troughs have been indicated in plains regions which cover 65% of Venus, and hypsometric comparisons between the two planets' elevation distributions revealed that while the earth has a bimodal height distribution, Venus displays a unimodal configuration, with 60% of the planet surface within 500 m of the modal planet radius. The effects of mapping the earth at the same resolution as the Venus observations were explored. Continents and oceans were apparent, and although folded mountains appeared as high spots, no indications of tectonic activity were discernible. A NASA Venus Orbiting Imaging radar is outlined, which is designed to detect volcanoes, folded mountain ranges, craters, and faults, and thereby allow definition of possible plate-tectonic activity on Venus.

Abstract: The reported analysis of Saturn's main magnetic field takes into account the data obtained by Voyager 1 during its close flyby of Saturn in November 1980. A magnetic field model for the analysis of Saturn's main field in which the distributed ring currents are explicitly modelled is constructed. The considered internal field parameters constitute a first approximation to Saturn's main field. Several model current systems that might be expected on physical grounds to be active in Saturn's magnetosphere are considered. It is pointed out that certain aspects of Saturn's main magnetic field relevant to the planet's interior have been discussed by Stevenson (1980). In particular, the unexpectedly small dipole moment seems to be consistent with the gravitational settling of helium, which leads to a much smaller electrically conducting and convecting region than would be expected of a homogeneous distribution of hydrogen and helium.

Abstract: Basalts are understood to be derived by partial melting from the mantles of their planets, and properties of the basalt samples we have been able to obtain (from Earth, the Moon, and the parent planets of the basaltic achondrite meteorites) have been an invaluable source of information about the composition and nature of the mantles of these bodies (Chapter 3). There is little doubt that basaltic volcanism has also been active on the planets that we have not been able to sample; in several cases, the surface morphologies and photometric properties of these planets strongly indicate the action of basaltic volcanism (Chapters 5 and 2). The purpose of this chapter is to infer as much as we can, by means other than sampling, about the compositions of planetary mantles. Our estimates of mantle compositions provide a basis for experimental petrologists to project the possible compositions of basalts that would be erupted on unsampled planets (Chapter 3). The clues we have to mantle compositions, apart from directly sampling them and the basalts that issue from them, are (I) the gross geophysical properties of the planets in question and (2) our estimates of their bulk compositions. Fragmentary chemical information comes to us from sources such as spectral studies of planetary atmospheres and surface regoliths, but most of our chemical constraints are based on broader considerations of the overall composition of the solar system and the early processes that appear to have caused the terrestrial planets to incorporate varying proportions of the elements. The geophysical constraints are reviewed in section 4.2, below; the admittedly speculative question of chemical processes that affected the origin and bulk compositions of the planets (cosmochemistry) is treated in section 4.3. Section 4.4 describes the process of planetary modelling by which the most probable mantle compositions, or compositional profiles, are derived from these inputs. Finally, section 4.5 carries out this modelling exercise for the terrestrial planets and Earth's moon, discussing the most likely mantle properties for each body.

Abstract: The concepts on the spatially-periodic condensation in the solar system have been considered in the light of the general theory of the evolution of the solar system. It has been shown that as protodisks arise and compress, the role of hydromagnetic effects weakens. After the stage of spatially-periodic condensation and accretion, the concentration of gas in protodisks decreases and the role of hydromagnetic effects increases again. Specific features of the formation of planets near the Sun and satellites near the planets can be explained if these peculiarities of the evolution are taken into account. The corresponding role of the above processes has been evaluated numerically.

Abstract: On the origin of the solar system, we have investigated the growing process of protoplanets by the capture of a number of planetesimals, cosidering that the motions of the planetesimals are described primarily by solutions of the restricted three-body problem but they are changed gradually by the effects of gas friction and mutual encounters. The results are summarized as follows. Once a protoplanet with mass of the order of 1025 g or 1026 g has been formed as a result of direct collisions of planetesimals, it is able to capture the the survived planetesimals within a sphere of its gravitational influence (the Hill sphere) and in periods of about 106 and 108 years it grows to the mass of the Earth (10 28 g) and that of Jupiter's core (10 20 g), respectively. Goldreich and Ward u and others have shown that planetesimals can be formed as a result of the gravitational instability of a thin dust layer within the primordial solar nebula. The mass of the planetesimals are of the order of 1019 g or smaller. In the next stage the planetesimals moving in the solar nebula will collide mutually and grow. It is probable that a part of planetesimals grow to a small number of massive bodies with mass of the order of 1025 g or 1026 g (which hereafter will be called protoplanets), while the mean mass of the remaining main part of the planetesimals is increased to the order of, say, 1021 g. The growing process after this stage, where the gravity of the protoplanets is strong enough to capture the survived planetesimals within their Hill spheres, is the main theme of this letter. Now, we consider a simplified initial condition that in a gas with density of about 1010 gcm3 a protoplanet of 1026 g and a great number of planetesimals of the same mass 1021 g (which will be called particles hereafter) are rotating around the Sun nearly in the ecliptic plane. The surface density of the planetesimals is taken to be 15 gcm2• This value and the above value of the gas density are taken from the results of Kusaka et al_2> for the primordial solar nebura near Jupiter's orbit. Both the gas and the protoplanet are assumed to be constantly in circular motions. The motion of a particle is primarily governed by the Sun and the protoplanet as described in the following by Eqs. (1) for the restricted three-body problem, but it is disturbed by the gas friction and the gravitational encounters with other particles. As usually made, we adopt a rotating frame (x, y) suce that the origin coincides with the center-of-masses of the Sun and the protoplanet and that these two bodies are fixed on the x-axis. Using a system of units in which the distance between the two bodies, the angular velocity of the rotating frame and the sum of the masses are all unity, we can write equations of motion for a particle as3>

Abstract: The formulation of a numerical integration program, used to construct ephemerides for satellites of the outer planets, is described. The equations of motion are derived, including (1) n massive integrated satellites, (2) m massive perturbing planets, (3) J2, J4 oblateness coefficients of the primary and each satellite, and (4) a barycentric coordinate system. Variational equations are also found: (1) 6n initial states and n masses of the integrated satellites, (2) J2, J4 of the primary planet, (3) the mass of the system, and (4) right ascension and declination of the pole. The formulation was used to construct the satellite ephemerides of Saturn for the Voyager mission.

Abstract: The results of two observations of stellar occultations of Neptune to determine if the planet has a ring system are reported. The sightings were made from Mt. Stromlo, Mauna Kea, and Cerro Tololo, noting that an equatorial ring would subtend only two arcsec of view. An upper accretion limit was defined to set the region around Neptune where rings, rather than satellites, could form. The intensities of the starlight from the two selected stars were recorded by photometers on magnetic tape during the occultation period. One of the stars did not occult, but passed through the entire region where a ring system might be present. No definitive evidence for rings was found, although an optical depth for a Neptunian ring was calculated at 0.07, with a width of more than 5 km and a radius of 31,400 km.

Abstract: The surfaces of the earth and the other terrestrial planets of the inner solar system are reviewed in light of the results of recent planetary explorations. Past and current views of the origin of the earth, moon, Mercury, Venus and Mars are discussed, and the surface features characteristic of the moon, Mercury, Mars and Venus are outlined. Mechanisms for the modification of planetary surfaces by external factors and from within the planet are examined, including surface cycles, meteoritic impact, gravity, wind, plate tectonics, volcanism and crustal deformation. The origin and evolution of the moon are discussed on the basis of the Apollo results, and current knowledge of Mercury and Mars is examined in detail. Finally, the middle periods in the history of the terrestrial planets are compared, and future prospects for the exploration of the inner planets as well as other rocky bodies in the solar system are discussed.

Abstract: Knowledge of the size distribution of comets and asteroids can be obtained from two sources. First the planet Earth can be regarded as a detector and the diameter distribution of Earth craters used to assess the mass distribution of the incident bodies. Secondly observations from Earth of the characteristics and orbits of comets and asteroids can lead to their collision probabilities and mass distributions. Simplistically it can be stated that the Earth craters have been produced by small incident objects whereas the comets and asteroids that are easily seen are the large ones. This paper seeks to relate these diverse sources of information.