Astronomy Picture of the Day (APOD) on October 22, 2026 presented an image of a white dwarf designated WD J1330+6435, which astronomers have named the first known "green star." For a long time, it was believed that stars could not appear green due to the peculiarities of how the human eye perceives the combination of wavelengths they emit—even if a star emits maximally in the green part of the spectrum, the resulting perceived color typically shifts toward white or a bluish tint. However, observations of WD J1330+6435 revealed that its atmosphere possesses an unusual chemical composition, which leads to selective absorption and re-emission of light at certain wavelengths. This creates an effect whereby the star actually appears greenish when observed under certain conditions. White dwarfs are compact remnants of stars that have exhausted their thermonuclear fuel reserves, and their atmospheres can contain unusual combinations of elements that significantly affect the observed color and spectrum. The discovery of such an object is of considerable interest to astrophysicists, since previously "green stars" were considered more of a theoretical possibility than an actually observable phenomenon. The study of WD J1330+6435 may help scientists better understand the processes occurring in the atmospheres of white dwarfs and refine models of stellar evolution at late stages of their lives. The APOD project, which publishes daily images and explanations of cosmic objects by professional astronomers, has presented this finding as a rare and remarkable example of the diversity of stellar objects in the Universe.