Summary: The first satellite images of the Pacific nation of Tonga after Saturday's volcanic eruption emerged Tuesday. The photos show the islands coated in ash. Despite the violent explosion, the Tongan government has reported just three deaths. The status of two smaller islands in its chain is still unknown. John Yang takes a closer look at the science behind the volcano, its explosion and aftermath. PBS NewsHour is supported by - https://www.pbs.org/newshour/about/funders
