Nasa's Unexplained Files

3:00 AM to 4:00 AM

Thursday 17 April

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 Science +1 at 3:00 AM, Thursday 17 April. (Subtitles.)

Topics

Education ➝ Science ➝ Factual Topics

Unexplained ➝ Mysteries