Comets are small celestial bodies orbiting around the Sun. They are remnants left over from the formation of the solar system; their interiors store original material of the planetary disk within the solar system. They are thus "fossils" for studying the early solar system. According to their orbital periods, comets are classified as long-period comets (orbital period P > 200 years) and short-period comets (P 2 gas ice, the polymerization reaction of cyanides, the crystallization of amorphous water ice, the annealing process of amorphous water ice, the thermal decomposition effect, and the electrostatic supercharge phenomenon. We then summarize the evolving activity of long-period comets as they travel from the Oort Cloud to the vicinity of their perihelions. We analyze unique properties of long-period comets, including such special phenomena as changes in dust color, coma structure, and tail structure. Finally, we summarize currently unresolved scientific questions, and then the entire paper.
Yingqi et al. (Thu,) studied this question.