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.

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.

A science-oriented advocacy group advanced its famous clock to 89 seconds Tuesday, the closest it has ever been.