New results in comet research

Comets are kilometer-sized icy conglomerates of frozen gases and dust particles which move around the Sun in an assembly called “Oort's cloud” in the outer parts of the planetary system. Only those which are ejected towards the Sun by the perturbations of passing stars will evaporate gases and dust while they are near the Sun. This material forms the large coma and the tails which make up the characteristic phenomenon of a comet. The spectral analysis has yielded that water is the main constituent of a comet, other molecules are simple compounds of H, C, O and N. — The ESA is planning a space mission to Comet Halley in 1986.