Nuclear doomsday clock

The Doomsday Clock is a symbolic clockface maintained since 1947 by the Board of Directors of the Bulletin of the Atomic Scientists. It uses the analogy of the human race being at a time that is a 'few minutes to midnight' where midnight represents destruction by nuclear war.

The clock was started at seven minutes to midnight during the Cold War in 1947, and has subsequently been moved forwards or backwards at intervals, depending on the state of the world and the prospects for nuclear war.

As of 2004, the clock is back at seven minutes to midnight, after recent deterioration in international relations. Each time nuclear conflict comes closer, it is moved forward, and vice versa. It has been moved 17 times.

Important events which have resulted in the changing of the clock include:

First testing by the Soviet Union of a thermonuclear device in 1949. Clock changed to three minutes to midnight.

United States and Soviet Union test thermonuclear devices within nine months of one another in 1953. Clock changed to two minutes to midnight.

United States and Soviet Union sign the Partial Test Ban Treaty in 1963. Clock changed to twelve minutes to midnight.

United States and Soviet Union sign the Strategic Arms Reduction Treaty in 1991. Clock changed to seventeen minutes to midnight.

2002, Little progress on nuclear disarmament. United States rejects a series of arms control treaties and announces withdrawal from Anti-Ballistic Missile Treaty. Terrorists seek to acquire nuclear weapons. Clock changed to seven minutes to midnight.