| Popis: |
Information on the dynamics of interplanetary dust is obtained by observations of radio-meteors, zodiacal light, thermal infrared emission, and by measurements with in-situ detectors on board Earth satellites and deep spaceprobes. These methods are sensitive to different meteoroid sizes (mm- to sub-micron sized) and refer to different regions of space. Bigger particles (> 10-9 g) move on bound Keplerian orbits and are dynamically dominated by solar gravity, while the trajectories of particles smaller than 10-10 g are strongly influenced by radiation pressure and electromagnetic interactions. Modelling interplanetary dust is done by dividing the whole meteoritic complex into dynamically distinct populations. Divine's (1993) model identifies five dynamically different populations of interplanetary meteoroids: bigger particles are described by the “core”, and “asteroidal”-populations, intermediate sizes by the “halo”-population, and small particles are included in the “eccentric” and the “inclined”-populations. The intermediate and the small particle populations, in particular, have to be redefined for several reasons: new data are available which require the consideration of hyperbolic orbits and the inclusion of radiation pressure and electromagnetic forces. New small particle populations are interstellar dust and beta-meteoroids. |
