Nasa's Unexplained Files

4:00 PM to 5:00 PM
Tuesday 24 December
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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 4:00 PM, Tuesday 24 December. (Subtitles.)
Topics
Education ➝ Science ➝ Factual Topics
Unexplained ➝ Mysteries