Giacobini-Zinner cometIn 1900, Michel Giacobini in France discovered a comet, which was rediscovered by a German, Ernst Zinner, on 23 Oct 1913, and since named the Giacobini-Zinner comet. It returns to the vicinity of the earth every six and two-thirds years. This comet became the first to be visited by a spacecraft. On 11 Sep 1985, the International Cometary Explorer (ICE) flew through its gas tail, 7,800-km downstream from the nucleus, at a speed of 21 km/sec. The nucleus was estimated to be 2.5-km across at its widest diameter. Instruments detected carbon monosulfide and hydroxyl molecules in the comet. The comet is the progenitor of the Draconid meteor shower, visible annually in early October, which produced intense meteor displays in 1933 and 1946. |