Long-period comets are celestial objects that take more than 200 years to complete one orbit around the Sun. They originate from the Oort Cloud, a distant region filled with icy bodies located far beyond the orbit of Neptune. These comets can appear from any direction in the sky and are often unpredictable in their arrival. When a long-period comet approaches the Sun, the heat causes its icy nucleus to vaporize, creating a glowing coma and a tail that can stretch for millions of kilometers. Famous examples include Comet Hale-Bopp and Comet Hyakutake, which captivated skywatchers during their appearances in the late 20th century.