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 are often unpredictable and can appear suddenly in the night sky. Their orbits are highly elliptical, which means they can travel far into the outer solar system before returning close to the Sun. As they approach, the heat causes their ices to vaporize, creating a glowing coma and tail that can be visible from Earth.