Comets are small celestial bodies composed of ice, dust, and rock that orbit the Sun in highly elliptical trajectories. They are often referred to as "dirty snowballs" because of their icy composition. Comets are believed to be remnants from the early solar system, and studying them can provide valuable insights into the formation and evolution of the solar system. Comets typically have a glowing coma and a tail that forms as they approach the Sun and the heat causes their ice to vaporize. Scientists study comets to learn more about their composition, structure, and behavior, as well as their potential role in delivering water and organic molecules to Earth. They also investigate the potential threat that comets pose to Earth in terms of impact events.