Discovery of 21P/Giacobini–Zinner

Comet 21P/Giacobini-Zinner is a short-period comet discovered by the French astronomer Michel Giacobini at the Nice Observatory, and recovered in a later return by the German astronomer Ernst Zinner, who is credited in its name. It orbits the Sun about every six and a half years. The comet is the parent body of the Draconid meteor shower, seen in October, which occasionally produces spectacular displays. In 1985 it became the first comet to be visited by a spacecraft, when the International Cometary Explorer, a repurposed NASA satellite, flew through its tail and measured the plasma and magnetic field around it.

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