Apollo 10 astronauts heard eerie ‘outer spacey’ music when they were on the dark side of the moon, declassified Nasa audio shows

The three astronauts on the mission were the furthest from the Earth that any human has ever been

Apollo 10 astronauts heard “eerie” and unexplained “outer spacey” music as they passed around the dark side of the Moon, it has been revealed.

New audio, declassified by Nasa, captures the moment that the Apollo 10 astronauts heard strange sounds as they passed around the far side of the Moon.

The astronauts’ strange experiences were first revealed in previously declassified transcripts of their discussions as they floated around the moon. The sounds came about as the astronauts took part in a test that saw them travel further from the Earth than ever before — 220,820 nautical miles — and far out of contact with Earth.

Throughout that time, the astronauts discuss the strange music.

“That music even sounds outer-spacey, doesn’t it?” one of the astronauts asks. “You hear that? That whistling sound?”

“Boy, that sure is weird music," lunar module pilot Eugene Cernan says in the notes. “We’re going to have to find out about that,” his colleague command module pilot John Young says.

It still isn’t clear where the strange sounds were coming from.

Particles in space might have interfered with the astronauts’ radios, scientists have suggested. The Cassini spacecraft picked up the same sounds from Saturn — though the charged particles in that case come from moving through Saturn’s environment, but the Moon doesn’t have an atmosphere or magnetic fields.

The sounds might also have come about as the two radios interfered with one another. But astronauts have suggested that the scientists would have been used to hearing those kinds of sounds.

It also isn’t clear known why the information stayed secret. But it is likely that it was kept hidden because of the US government’s policy of encouraging astronauts to stay quiet about unusual psychological events in space, so that public trust in the space missions would stay strong.

The astronauts mention in the recording that they aren’t sure whether to mention what they hear, or that anyone would believe them if they did.

“That’s just like something from outer space, really. Who’s going to believe it?” asks Mr Cernan. “Nobody. Shall we tell them about it?” Mr Young replies.

The two conclude in the transcript that they “ought to think about it some”.

Apollo 10 Hasselblad image from film magazine 35/U – Lunar Orbit, Trans-Earth CoastProject (Project Apollo Archive/Nasa)

The transcript continues as Mr Cernan says “Hell, I just want to get out of this suit”, before the astronauts continue on their mission.

The astronauts never publicly discussed the sounds.