[en] Methods of processing VEGA-TV observations of the nucleus of P/Halley and derived scientific results are summarized. The existence of lineamentary surface structures is interpreted as an indication for boundary zones between km-sized blocks, building the cometary nucleus. The consequences for cometary origin were investigated. (author). 3 figs., 5 refs

[en] Within a planetogonic model the self-gravitationally caused formation of pre-planetary and pre-satellite rings from an earlier thin disk is reported. The theoretically derived orbital radii of these rings are compared with the orbital levels in the planetary system and the satellite systems of Jupiter, Saturn and Uranus. From this comparison it is concluded that at the radial position of Saturn's newly discovered outer ring an early pre-satellite ring of more or less evolved satellites could have existed. These satellites should have been disturbed in their evolution by the gravitation of the neighbouring massive satellite Titan. The comparison also may indicate similarities between the asteroidal belt and the newly discovered outer ring of Saturn

[en] It is shown by linear stability analysis that a preplanetary (presatellite) disk of dust and gas with Keplerian velocity field can become unstable due to the collective self-gravity of the disk. The radial distribution of rings, which may result from this instability, is derived. These rings later on can be the formation sites for planets around the Sun and for satellites around the planets. The derived orbits are shown to be in good agreement with that of the planets and the satellites (of Jupiter, Saturn, and Uranus). Predictions and conclusions seem to be possible for the existence of three yet unknown Uranian satellites, the origin of the early Moon and the possible radial extension of the planetary system. (Auth.)

[en] Pressure of solar electromagnetic radiation is able to cause an outward flow of small particles and gaseous pre-planetary matter. This outflow can be stopped at a characteristic radius by the inward flow of pre-planetary matter due to viscous interactions. The chemical boundary between terrestrial and giant planets or the gap in the radial mass distribution seem to be correlated with this characteristic radius. The existence of similar gaps in the satellite systems of Jupiter, Saturn and Uranus can be used to estimate early properties of these planets. (author)

[en] Thermomechanical stresses can have a remarkable influence on the physical properties and morphology of cometary nuclei. It is shown by this paper, that resulting growing cracks and clefts give appropriate conditions for a rotationally and/or gas pressure triggered split of companions from the surface of the cometary nucleus. Observed properties of activity phenomena of comets and properties of cometary companions can be understood within this scenario. (author)

[en] Rotational properties (rotation, precession) of the nucleus of comet Halley are investigated on the basis of image processing results of VEGA and GIOTTO and a compilation of recurrence periodicity of 71 events of activity of P/Halley in 1986. It is shown that the analysis of recurrence periodicity gives strong indications for the two periods of 2.2 days and 4.9 days. These periods are well compatible with the three known positions of the nucleus of comet Halley, as they were derived from image processing of the data of VEGA-1 and -2 and GIOTTO. The resulting long-axis mode of rotation and precession can be described by a 4.9 days rotation around the long axis which is precessing once around the total angular momentum vector M with a period of 2.2 days and with an angle θ₁ = 73^o between the long axis and the spatially fixed M, while the angle ω₁ between the vector Ω of angular velocity and the long axis is given by ω₁ = 52^o. (author)

[en] The main directions of modern planetogonic theories are reviewed shortly and confronted with 'reconstruction characteristica' which have to be fulfilled by every realistic planetogonic theory. It is especially the existence of comparable structures in the four satellite systems of Sun, Jupiter, Saturn and Uranus which indicates the action of structuring large-scale collective gravitational instabilities in the preplanetary disk. The resulting planetogonic scenario is able to explain the observed radial structures in the four systems (and to formulate correct predictions). Properties of the preplanetary disk are derived from this scenario. (author)

[en] Fundamental approaches to the problem of the formation of planetary and satellite systems are considered. Emphasis is placed on the hetegony principle and its proposed generalization to a formation principle including the central body, and a restricted actualistic principle. Relevant characteristic parameters (i.e., energy levels of orbits, mass distribution in satellite systems, and angular momentum) for identifying the formation processes are examined, and possible future planetological tasks that should be undertaken in the foregoing framework are discussed

[en] At the end of the sixties it became obvious that two-dimensional dynamo models can explain nearly all facts, which had been found morphologically for mean annual Sq-fields. During the recent decade new or improved methods to measure electric fields (e.g. incoherent sy.ter facilities) and to investigate great data files have been developed. New informations received with these methods about the existence of regular variations of the Sq-field in dependence on season and universal time andtabout the electric field have been summarized in Section 2. All attempts to describe also these variations with a two-dimensional dynamo mooel did not lead to any success, but showed a strong theoretical over-estimation of the asymmetries. Therefore, it must be concluded that three-dimensional plasmaspheric current systems, taking into consideration the coupling between both hemispheres along the high-conducting magnetic field lines, are needed in order to explain the regular variations of the Sq-field. The basic equations for two- and three-dimensional dynamo models, different methods for the solution of these equations and the resulting models from different authors are compiled and discussed (Section 3). Based on all morphological and theoretical results a plasmaspheric-ionospheric current system has been constructed and some properties of the plasmaspheric field-aligned current distribution, have been derived. (orig.)