Astronauts of the Apollo 10 managed to hear some arcane music while visiting the Moon.
The crew was orbiting the Moon when their ship suddenly was filled with whistling sounds, which differed from all the things the men had experienced earlier.
Retired astronaut Al Worden from Apollo 15 said that if he had been there without any connection to NASA, he would have been scared.
The record has remained secret for about 40 years. Only in 2008, certain data from the Apollo missions was revealed, and now everyone can learn it from documentaries on TV. The third season starts on Tuesday.
Despite different theories, specialists cannot explain where the music came from.