Picture of the Day - Volcanic Activity at Kilauea

Volcanic fog—vog—swirls around the Hawaiian Islands in this satellite image. Vog is formed when sulfur dioxide gas emitted from a volcano reacts with oxygen and water vapor.

The reactions form tiny drops of sulfuric acid and other sulfates, which create a visible haze. Since March 12, 2008, emissions of sulfur dioxide (the gas that forms vog) from Kilauea volcano have been elevated: 800 metric tons (1,800,000 pounds) per day in early December 2009, compared to a 140 metric ton per day (310,000 pounds) average from 2003–2007.

Volcanic Activity at Kilauea, Hawaii. Credit: NASA

The Moderate Resolution Imaging Spectroradiometer (MODIS) aboard NASA’s Terra satellite captured this natural-color image on December 9, 2009.