The Doomsday Clock is a symbolic clock: a metaphor for how close humanity is to self-annihilation, according to the Bulletin of the Atomic Scientists.

The Doomsday Clock now stands at 89 seconds to midnight, the closest to catastrophe in its nearly eight-decade history. Here's a look at how — and why — it's moved.

The Doomsday Clock, a symbolic tracker that represents the likelihood of human-made destruction, was updated Tuesday to 90 seconds to midnight—the closest to global catastrophe it’s ever been ...