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 Bulletin of the Atomic Scientists, which is the group that sets the time of the clock, introduced it back in 1947 to predict the chance of annihilation from a range of threats

The “doomsday clock” symbolising how close humanity is to destruction ticked one second closer to midnight Tuesday as concerns on nuclear war, climate and public health were jolted by US President Donald Trump’s return.