What is the Doomsday Clock? It's 2025 and scientists have reset the clock closer to midnight and global catastrophe. Here's what it all means.

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.

Scientists and global leaders revealed on Tuesday that the "Doomsday Clock" has been reset to the closest humanity has ever come to self-annihilation.