On the 50th anniversary of the Moon landings, three original video tapes of the event have been sold at auction for an interstellar price.

Key points: The tapes run for nearly two-and-a-half hours, showing the entirety of the Moon walk as seen by NASA Mission Control

The tapes run for nearly two-and-a-half hours, showing the entirety of the Moon walk as seen by NASA Mission Control Sotheby's auction house says the footage is "sharper and more distinct" than those available elsewhere

Sotheby's auction house says the footage is "sharper and more distinct" than those available elsewhere A former NASA intern had bought the tapes in 1976 for just $US217

The Sotheby's auction house sold three original NASA videotapes of Neil Armstrong and Buzz Aldrin's landing on the Moon for an eyewatering $US1.82 million ($2.58 million) — more than 8,000 times what a NASA intern paid for them in 1976.

Back then, Gary George bought them from a government surplus auction, Sotheby's said, adding the videos had not been restored, enhanced or remastered, and were the "earliest, sharpest and most accurate surviving video images of man's first steps on the Moon".

"Fifty years ago today, we achieved the world's greatest human accomplishment, and what we universally recall about that event is best documented on these tapes," Sotheby's Cassandra Hatton said in a media release.

"We are truly over the Moon about today's outstanding result."

The tapes show images now famous worldwide, including Armstrong's first step, Aldrin climbing down the lander's ladder, the planting of the American flag and Aldrin bouncing along the lunar surface.

The images are "sharper and more distinct" than those shown elsewhere, Sotheby's added.

The tapes run for two hours and 24 minutes, showing the entirety of the Moon walk as seen by Mission Control, including the phone call with the-US president Richard Nixon.

The buyer of the tapes is unknown.

Former intern cashes in

Mr George was interning at NASA in 1976 while studying engineering at Lamar University, and occasionally went to government surplus auctions, according to Sotheby's.

He paid $US217.77 for a lot of more than a thousand reels of magnetic tape that had belonged to NASA.

Mr George sold and donated some of those tapes, but after his father noticed some of them were labelled "APOLLO 11 EVA" and "vr2000 525 Hi Band 15 ips", he decided to keep three of them.

The tapes suddenly increased in monetary value when, in 2008, NASA began trying to locate the original tapes for the Moon landing's 40th anniversary.