Nasa's Unexplained Files

2:00 AM to 3:00 AM

Tuesday 21 January

Earth's Secret Aliens

Season 3 Episode 20 of 24

Geologists begin to ask questions about 'alien' deposits found on the Earth's surface - and the answer could shed light on the cause of history's greatest extinction event

Nasa's Unexplained Files airs on Discovery History at 2:00 AM, Tuesday 21 January. (Subtitles.)

Topics

Education ➝ Science ➝ Factual Topics

Unexplained ➝ Mysteries