The shower is the Geminids, arriving every mid-December when Earth plows through the stream of meteoroids sharing the orbit of asteroid (3200) Phaethon. Most meteor streams comprise sand- to pea-sized rocky pebbles liberated from comets as the sun sublimates (turns directly from ice to gas) the frozen water, ammonia, carbon dioxide, and other ices on their surfaces in which the particles are embedded.

Chris Anderson manages the College of Southern Idaho’s Centennial Observatory in Twin Falls. He can be reached at 208-732-6663 or via email at canderson@csi.edu .

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