Nasa's Unexplained Files

9:00 AM to 10:00 AM

Tuesday 31 December

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 at 9:00 AM, Tuesday 31 December. (Subtitles.)

Topics

Education ➝ Science ➝ Factual Topics

Unexplained ➝ Mysteries