Carl Sagan

Astronomer. Three documents tie him to this research: his 1963 paper suggesting an alien base might be kept on the Moon, his 1975 criterion that rectilinear order is a sign of intelligence seen from orbit, and his 1986 letter to Mark Carlotto agreeing that the 'trick of lighting' dismissal of the Face was in error.

On the record

• Sagan 1963, Planetary and Space Science 11, p. 497: Earth visited 'possibly ~10^4' times; a base may be 'maintained (possibly automatically)' and 'the Moon seems one reasonable alternative'.
• Sagan 1975: rectangular arrays and departures from thermodynamic equilibrium as signs of intelligence.
• Letter to Carlotto, 10 September 1986 (shown on Reality Check at 1:31:40).
• Used Carlotto's 3D reconstruction of the Face in Cosmos: 'if we're going anyway, there's no harm in taking a look.'

Cases (1)

• 1976The Face on Mars

Connected