Credit: Dave Harlow/USGS
This photo, taken on June 12, 1991, shows the eruption column of Mount Pinatubo on Luzon Island in the Philippines. The eruption--the largest on Earth in the past 100 years--ejected particles into the stratosphere, more than 6 miles above the planet's surface. New research uses ice core data to rewrite the past 2,600 years of large stratospheric eruptions like this one.