WATCH: Apollo 10 Astronauts Heard ‘Weird’, ‘Eerie’ Sounds on the Dark Side of the Moon

Astronauts Eugene A. Cernan, Thomas P. Stafford and John W. Young pose for a publicity photo for the Apollo 10 mission in 1969. (PHOTO CREDIT: NASA)

NASA astronauts in orbit around the moon in 1969 heard a whistling sound described as “outer-spacy,” “weird,” and “eerie.”

Recordings of the strange sounds are featured on the Science Channel show “NASA’s Unexplained Files,” which will air Tuesday night at 10 p.m. ET.

The sounds were discussed in a conversation between Apollo 10 astronauts Eugene Cernan and John Young as their craft flew around the far side of the moon, CNN said.

Though the Apollo 10 audio and transcripts were not officially classified, there was “no way to get them to the public before the Internet,” the NASA History Office clarified Monday morning on Twitter.

The flight crew heard the sounds while on the dark side of the moon and while out of radio contact with NASA ground control, according to a report from the E.W. Scripps National Desk.

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SOURCE: USA Today, Doyle Rice