请调整浏览器窗口大小或者请使用手机查看!
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?
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.