Atomic scientists say we're two minutes closer to doomsday than we were in 1998.

The hands of the doomsday clock were moved to seven minutes to midnight, up from nine minutes to midnight when it was last reset four years ago.

For 55 years the clock has been maintained by a publication called the Bulletin of the Atomic Scientists. The chair of the Bulletin's board says it is never moved in response to a single threat. George Lopez says the time change this year reflects the greater possibility of terrorism, and concerns about the security of nuclear weapons material stockpiled around the world.

Clock moved up by two minutes

It's the 17th time the clock has been reset since it was established in 1947. On that day, like today, it was set at seven minutes to midnight.

"Midnight" was originally defined as nuclear war. Now it is taken to mean the use of nuclear weapons anywhere on earth.