180420-N-OY339-1233 SIGONELLA, Sicily (April 20, 2018) Sailors line up in preparation for a foreign object debris (FOD) walk-down on the flight line at Naval Air Station (NAS) Sigonella during an Earth Day event. Earth Day is celebrated on April 22 and is a day where more than 193 countries hold events to demonstrate support for environmental protection. (U.S. Navy photo by Mass Communication Specialist 2nd Class Christopher Gordon/Released)