German scientists using a new technique said they detected a
slight chemical difference between Earth rocks and moon rocks.
Scientists said more study would be needed to confirm this
long-elusive piece of evidence that material from another body
besides Earth contributed to the moon’s formation some 4.5 billion
Scientists believe the moon formed from a cloud of debris launched
into space after a Mars-sized body called Theia crashed into young
Different planets in the solar system have slightly different
chemical makeups. Therefore, scientists believed moon rocks might
hold telltale chemical fingerprints of whatever body smashed into
Until now, evidence was elusive.
“We have developed a technique that guarantees perfect separation,”
of oxygen isotopes from other trace gases, Daniel Herwartz, with the
University of Cologne in Germany, wrote in an email to Reuters.
"The differences are small and difficult to detect, but they are
there,” added Herwartz, lead author of a paper on the discovery
published in this week’s issue of the journal Science.
The results indicate that composition of the moon is about 50
percent Thea and 50 percent Earth, the scientists said, although
more work is needed to confirm that estimate.
The team analyzed rocks brought back to Earth by NASA astronauts
during the Apollo 11, Apollo 12 and Apollo 16 missions to the moon,
which took place in 1969 and 1972.
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“This work is the first to claim to see such a difference in the
isotopes of oxygen,” said Robin Canup, a planetary scientist with
the Southwest Research Institute in Boulder, Colorado, who was not
involved in the research.
“The reported difference between the Earth and moon is extremely
small, small enough that I think there will be debate as to whether
the difference is real or an artifact of how one interprets the
data,” she added.
Meanwhile, other teams of scientists have been looking at titanium,
silicon, chromium, tungsten and other chemical elements, but so far
the lunar samples show no detectable differences from Earth samples.
(reporting by Irene Klotz)
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