NGC 6558 is a planetary nebula located in the constellation Sagittarius. It is approximately 2,000 light-years away from Earth and is known for its bright central star, which is a remnant of a dying star that has shed its outer layers. The nebula exhibits a round shape and is composed of ionized gas that glows due to the radiation from the central star. Discovered by John Herschel in 1836, NGC 6558 is part of a larger group of nebulae that showcase the life cycle of stars. Its distinct features include a complex structure with varying brightness, making it an interesting subject for astronomers studying stellar evolution.