Scientists have solved the 200-year-old mystery of the location of a massive volcanic eruption that spewed such a large volume of gases that it blocked sunlight, making the sun appear blue.

This story appears in the August 2018 issue of National Geographic magazine. Indonesia has 127 active volcanoes. Only the U.S. (168) and Russia (144) have more. Essential packing list: We landed ...

and Other Breakthroughs At 2 a.m., this photographer descended into an active volcano where miners extract sulfur from inside a blue-flame spewing crater.