http://www.cnn.com/2016/02/21/world/far-side-moon-music/ Did you hear that whistling sound too?" "Sounds like -- you know, outer-space type music." "I wonder what it is." This conversation, between Apollo 10 astronauts Eugene Cernan and John Young, as their craft flew around the far side of the moon, remained under wraps for over four decades. Out of radio contact with Earth and all alone on the far side of the moon, the astronauts were clearly not expecting to hear anything on their instruments. "You hear that? That whistling sound? Whoooooo," says Cernan on the recording. "That sure is weird music." It was so weird that the team debated whether or not to mention it to their superiors at NASA, out of fear that it could cast doubt on their suitability for future spaceflight.