Watch Now: EXPOSED: Do aliens exist? Glenn asks one of the few men who has walked on another world, Apollo 16 astronaut Charlie Duke, what he believes. Duke, who became a strong Christian after visiting the moon, explains why he wholeheartedly believes that UFOs exist, but that they’re better described as “demonic” than “extraterrestrial.” Plus, he shares his testimony and why faith in Jesus is the only thing that could top walking on the moon.