Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer. Io has its own cloud. Jupiter 's most active moon is visible on the left of the above false-color photograph , with its left side illuminated by sunlight. Here a plume of gas from the active volcano Prometheus also reflects sunlight. Surrounding the moon is a yellow haze originating from gas ejected by Io's volcanos .
Sodium atoms in the gas cloud are particulary efficient at reflecting yellow light .
Several points of light are background stars. Specific rights apply .