Mystery of how a meteor left Earth thousands of years ago, then came back

Baffled scientists are trying to unravel the mystery of how a meteorite left Earth’s atmosphere and somehow came back again.

Unlike boomerangs, meteorites don’t have a reputation for coming back around again, so when a black rock found in Morocco in 2018 seemed to have done just that, it left the scientific community confused.

The rock, whose official name is Northwest Africa (NWA) 13188, is a scientific first (that we know of) to have left the Earth’s atmosphere, gone into outer space and returned again.

The 646-gram piece of rock is remarkable not only for its journey but also its makeup.

NWA 13188 has a bubbly texture and contains crystals. Its chemical components suggest that the rock is made out of the minerals produced by molten minerals that come from volcanic activity.

It also possesses trace elements and oxygen isotopes, which suggests to scientists that it is not the typical meteorite that originates in space, but instead, it originated on Earth itself.

However, according to a geophysicist from the French National Centre for Scientific Research, Jérôme Gattacceca, who studied the rock and presented the findings, it has undergone an interesting journey in orbit.

Scientists can identify this because of the presence and concentration levels of Helium-3, Beryllium-10, and Neon-21, which suggest exposure to cosmic rays that are not present in Earth’s atmosphere.

Compared to other more traditional meteorites scientists have studied, the concentrations are lower on NWA 13188 but are still higher than rocks on Earth.

It is thought that NWA 13188 could have been expelled from Earth and in orbit for thousands of years.

Scientists said, “We consider NWA 13188 to be a meteorite, launched from the Earth and later re-accreted to its surface”.

Despite the rock originating on Earth, the team said it fits the definition of a meteorite since it has achieved orbit.

The definition states: “Material launched from a celestial body that achieves an independent orbit around the Sun or some other celestial body, and which eventually is re-accreted by the original body, should be considered a meteorite.

“The difficulty, of course, would be in proving that this had happened, but a terrestrial rock that had been exposed to cosmic rays and had a well-developed fusion crust should be considered a possible terrestrial meteorite.”

It is not yet understood how the rock came to be launched from Earth into space, as researchers said it still “remains to be determined”.

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