Pale blue dot: Earthrise, December 24, 1968

Cutting-edge technology reveals how one of history’s most important images almost didn’t happen. (Maria Popova)

Earthrise, Apollo 8, December 24, 1968 (NASA)

The Earth is a very small stage in a vast cosmic arena. (Carl Sagan)

The Pale Blue Dot, Voyager I (captured from 3.7 billion miles away), February 14, 1990 (NASA)