Carl Sagan - Cosmos - Eratosthenes
4:14
Carl Sagan Predicted The Mess 2021 Would Be 25 years Ago
9:00
Neil Tyson Demonstrates Absurdity of "Flat Earth"
1:36:01
Carl Sagan's 1994 "Lost" Lecture: The Age of Exploration
7:49
How the Ancient Greeks Proved that the Earth was Round
8:02
Carl Sagan - COSMOS - Evolution
2:07:07
The 1993 Bunyan Lecture: Carl Sagan - “Is There Intelligent Life on Earth?”
16:54
Carl Sagan testifying before Congress in 1985 on climate change
59:52