You're looking at a picture of the Vanuatu Archipelago, shrouded in vog — a word used to describe the kind of volcanic smog which is formed when gases from a volcano react with sunlight, oxygen and moisture. The results are stunning.
You can see the vog as a light blue-grey plume which arcs from the volcanic island. The other feature in the image is a band of silver-grey, running north-south, called "sunglint" — the reflection of the sun off the ocean as the image is acquired by the satellite. The image of Vanuatu Archipelago — a collection of volcanic islands about 1800km northeast of Australia — was captured by NASA's Aqua satellite earlier this month. [NASA]