A netizen asked Collins if he believes that there is "life outside of Earth" under the hashtag #AskMichaelCollins.
In a laconic but stunning answer, the veteran astronaut said: "Yes".
The answer resulted in a storm of tweets, with similar views suggesting that extraterrestrial life has evolved in other parts of our universe.
The NASA veteran played a critical role in the first manned Moon mission, alongside colleagues Neil Armstrong and Buzz Aldrin. In July 1969, the astronaut flew the Command Module vehicle around the Moon while astronauts Neil Armstrong and Buzz Aldrin landed on the surface for the first time in the history of humanity.
After retiring from NASA and the US Air Force as a major general in 1970, the former astronaut has been a vocal supporter of establishing a human presence on Mars.