Leap second
SCHRIEVER AIR FORCE BASE, Colo. (AFPN) -- The U.S. Naval Observatory Alternate Master Clock, located at the 2nd Space Operations Squadron's operations center, is accurate to within one second every 20 million years. The clock showed 23:59:60 Saturday as the squadron and USNO added the first leap second in seven years. (U.S. Air Force photo by Airman 1st Class Jason Ridder)