The cool white dwarf WDJ1330+6435 has accreted sodium-rich rocky material from its planetary system into its atmosphere. The immense atmospheric density causes the sodium to absorb light over a broad range of yellow, orange, and red wavelengths, giving the WDJ1330+6435 a ghostly green appearance (left). The cool white dwarf WDJ0902+2010 has a deep convection zone within its helium dominated outer envelope. The convection zone has reached the white dwarf core, lifting interior carbon to the surface, and forming carbon molecules. These C2 molecules strongly absorb light across the optical range, including blue, green, and yellow wavelengths, resulting in WDJ0902+2010 appearing pink to the human eye (right) Image: Mark A. Garlick/University of Warwick

Despite the name, the universe’s white dwarfs can glow in a wide range of colors—even green. For the first time, astronomers have spotted a star that appears green to the human eye, and the reddest ever recorded.…