Strangest fact
A real NASA transcript contains an astronaut reporting an unknown object in polar orbit, and a different astronaut announcing that Santa Claus exists. Read out of context, years later, both sound like hidden messages.
Apollo 8 was the first crewed flight to the Moon. After ten orbits on Christmas Eve 1968, the crew had to fire their engine on the far side, out of contact, to head home. If it failed they would be stranded. NASA's history page describes mission control waiting for word, which came when Lovell radioed: Roger, please be informed there is a Santa Claus.
Three years earlier, on December 16, 1965, the Gemini 6A crew of Wally Schirra and Tom Stafford played a planned Christmas joke. Stafford reported an object, looks like a satellite going from north to south, up in a polar orbit,
and said it looked like it might re-enter soon. Then the two played 'Jingle Bells' on a small harmonica and bells they had brought aboard. The Smithsonian's National Air and Space Museum keeps the harmonica, and calls these the first musical instruments played in space.
Some UFO books later claimed that 'Santa Claus' was a NASA code word for an alien spacecraft, and that Lovell was secretly reporting one. The Scottish science writer Duncan Lunan, writing in 2024, noted that the claim is still repeated but that the fact that both remarks were made at Christmas is rarely mentioned, and that, as far as he knew, no astronaut has used the phrase in space since.