#coma  (astronomy) the luminous cloud of particles surrounding the frozen nucleus of a comet; forms as the comet approaches the sun and is warmed
  supertype:  cloud  any collection of particles ($('<' #physical_phenomenon replaced by #natural_object because #cloud.atmospheric_phenomenon already exists and a clous a color, a mass, ... like all natural objects)$ e.g., smoke or dust) or gases that is visible
  part of:  comet  (astronomy) a relatively small extraterrestrial body consisting of a frozen mass that travels around the sun in a highly elliptical orbit

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