| http://www.w3.org/ns/prov#value | - Cometary nuclei are composed of an amalgamation of rock, dust, water ice, and frozen gases such as carbon dioxide, carbon monoxide, methane, and ammonia.[12] As such, they are popularly described as dirty snowballs" after Fred Whipple's model.[13] However, some comets may have a higher dust content, leading them to be called icy dirtballs".[14] Research conducted in 2014 suggests that comets are
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