Experts discuss the many possible ways that could spark the beginning of the end for the universe, including when and why it would happen.

Until recently, black holes were only theoretical; scientists know that millions exist, and some of them have the potential to be lethal to earth.

Aliens could be lethal killers who want to invade and plunder our world. A team of experts investigate extra-terrestrial beings and their threat to human life.

More than 100 million pieces of small space debris are floating around the Earth; a collision between two of these objects in low Earth orbit could be catastrophic.

When a massive star dies, it can direct a blast of radiation that would obliterate life on Earth. What are the chances of this event occurring?

Earth is hit by 100 tons of rock from space every day. Most burn up in the atmosphere, but a single rock wiped out the dinosaurs. Could it happen again?