2019 will mark the 50th anniversary that of the Apollo 11 mission when U.S. astronauts, including Neil Armstrong, became the first men to walk on the Moon. But in 2018, Sotheby's will auction off a small part of it – and it could worth as much as $1 million.

Next month, the auction house will sell three tiny bits of the celestial body that were brought back from the the 1970 Soviet Luna-16 mission. They were given to Nina Ivanovna Koroleva, widow of Sergei Pavlovich Korolev, the head rocket engineer in the Soviet space program during the 1950s, Sotheby's said on its website.

Previously sold by Sotheby's in 1993 for $445,000, the Moon fragments are estimated to be worth between $700,000 and $1 million and are the only fragments of the satellite that can be sold legally.

12-POUND ROCK FROM MOON SELLS FOR MORE THAN $600,000

"Authentic lunar samples available for public acquisition may be qualified as extremely rare, as title to lunar samples remains with the entities that collected them — the United States during the Apollo 11-17 missions, and the USSR (succeeded by the Russian Federation) via the Luna-16, -20, and -24 missions — as well as with the countries gifted the Apollo 11 samples and the Apollo 17 Goodwill moon rocks on behalf of the Nixon Administration," Sotheby's writes on its website.

Sotheby's continues: "These samples are subject to laws governing public gifts, and in most cases, as in the United States, the law does not currently allow for public gifts to be transferred to an individual. As such, this is the only known, documented lunar sample to have been gifted to a private individual."

The Moon rocks are very small, with the two largest pieces measuring two by two millimeters, CNN reports. By contrast, a 12-pound lunar meteorite sold earlier this month at an auction in Boston for $612,500.

NEIL ARMSTRONG MEMORABILIA GOES ON THE BLOCK

Also included in the auction is a complete Gemini spacesuit with helmet, estimated to be worth between $100,000 and $150,000; a painting from Apollo 12 astronaut Alan Bean, entitled "A Nice Place to Visit," estimated to be worth between $20,000 and $30,000; a Soviet LK-3 Lunar Lander Model, estimated to be worth between $12,000 and $14,000 and several other items.

The auction will be held on Nov. 29, 2018.

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