NGC 6818, also known as the "Little Gem Nebula," is a planetary nebula located in the constellation Sagittarius. It is approximately 6,000 light-years away from Earth and has a diameter of about 0.5 light-years. The nebula is notable for its bright central star, which is a remnant of a dying star that has shed its outer layers. Discovered by John Herschel in 1836, NGC 6818 is characterized by its compact size and vibrant colors, which are produced by the ionization of gases. The nebula's structure includes a bright core surrounded by a faint halo, making it a popular target for amateur astronomers and astrophotographers.