Every bit of steel in the car you drive has been measured as to its capability to withstand certain forces — pushing and pulling. Machines like this do the measuring.
Jennifer Lauren Lee/NIST PML
The eruption of Mount Pinatubo in the Philippines in 1991 spewed almost 20 million tons of sulfur dioxide into the atmosphere, causing worldwide temperatures to drop half a degree on average.
Arlan Naeg/AFP/Getty Images