For years scientists have believed that the Moon was created after a clash of a large celestial body into the Earth about 4.5 billion years ago. However, a new chemical analysis of lunar rocks, as regarding the amount of titanium, has found them to be too similar to that of terrestrial rocks, which disapproves the hypothesis that the Moon was formed from two different bodies.
Researchers at the University of Chicago, led by geochemist Junjun Zhang, used a mass spectrometer to make the most accurate measurement ever made. They compared the samples of lunar rocks, brought to Earth after the Apollo missions of the 70’s, to those terrestrial.
The scientists found that the ratio of titanium isotopes, contained in both samples, is virtually identical (about 4 parts per million). But this similarity does not justify that the Moon, from a geological point of view, is not only a part of the Earth, but a mixture of two celestial bodies.
Normally, the chemical “signature” of the Moon should contain isotopes of both “parents”, the Earth and the other unknown body that collided with our planet. This body should have a different geochemical composition from the terrestrial one, since the studies of meteorites fallen to the Earth from space show that they have abundant titanium isotopes (up to 600 parts per million).
Scientists have calculated that after the horrific collision the Earth contributed approximately 60% of the Moon substance and another body at least 40%. Thus, the Moon should not have identical to the terrestrial isotope of titanium in its territory.
An alternative theory which would explain better the new data is that the Moon was created from a part of the Earth that cut off, while the centrifugal force of our planet was stronger than its centripetal force of gravity.
However, this scenario has several disadvantages. Anyway, there is still no definitive answer to how the Moon was created.