Comets are frozen leftovers from the formation of the solar system composed of dust, rock, and ices that range in size from a few to tens of miles wide. As comets orbit closer to the sun, they heat up and spew gases and dust forming a glowing head and tail that can stretch millions of miles. The document provides background on comets, the differences between comets and asteroids, the history of observing comets, examples of specific comets like Halley's Comet, and details on Comet Neowise that was visible in the summer of 2020 including photographs of it taken over Mount Shasta and in a Costco parking lot.