Discover the cosmos! Each day a different image or photograph of our fascinating universe is featured, along with a brief explanation written by a professional astronomer.
April 28, 1997
Explanation: Io has its own cloud. Jupiter's most active moon is visible on the left of the above false-colour photograph, with its left side illuminated by sunlight. But what is happening on Io's right side? Here a plume of gas from the active volcano Prometheus also reflects sunlight. A second active volcano, Pele, is also visible: marked by the red spot just below Io's centre. 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.
Authors & editors:
NASA Technical Rep.: Jay Norris. Specific rights apply.
A service of: LHEA at NASA/ GSFC
&: Michigan Tech. U.