One possible explanation for how the moon formed is that another planet, which some scientists refer to as Theia, collided with Earth billions of years ago. Scientists have attempted to find enough differences in moon rock samples compared to rocks found on Earth to prove that the moon was created when our planet collided with another world in the distant past. Now, they may have discovered enough of a difference in the lunar rocks, though it’s a minor one, to validate the theory that the moon has both Earthly and other-worldly origins.
Three lunar rocks which Apollo astronauts collected from the moon’s surface and returned to Earth with in the 1960s have been re-analysed by scientists from Germany’s Georg-August-Universität Göttingen. The rocks might offer proof that they are different enough from Earth rocks that they came from another planet when it collided with our own.
After another world, let’s say one called “Theia,” slammed into Earth, the theory goes that molten rock was formed and flung up into orbit around our planet where it cooled and became Earth’s largest natural satellite. In mythology, the Greek goddess, Theia, was the mother of the moon.
The new analysis the scientist did on the lunar rocks indicated a subtle difference between them and any that have so far been found on Earth. The difference is that the lunar rocks the Apollo astronauts returned with contain a small percentage of a form of oxygen called oxygen-17, a somewhat greater percentage of it than is found in Earth rocks. Oxygen-17 is different from the more typical type of oxygen on Earth in that its atoms have nine neutrons instead of eight.
The lunar rocks are only 0.012 percent richer in oxygen-17 than rocks of Earthly origins. That difference, as small as it is, might be enough to validate the theory that the moon was the result of Earth’s having collided with another planet billions of years ago, a planet which also possibly had enough oxygen to sustain life at one time.
According to Time and other sources, scientists discovered this minuscule difference when they placed the lunar rocks into a fluorine gas-filled chamber. Using a laser beam, they then vaporized a tiny bit of the lunar rocks, and removed the vapor and gas from the chamber. The vapor and gas was analyzed using a chromatograph. The oxygen within the lunar samples was separated from any of the other gases, and the team of scientists doing the analysis were finally able to detect the difference in the amount of oxygen-17 that had eluded other scientists up until then.
After they noticed the subtle distinction in the amount of oxygen-17, the scientists also looked back at previous samples collected by Apollo 1, 12, and 16 astronauts and detected the exact same difference. Team leader, Daniel Herwartz, stated that the difference is enough to draw the conclusion that “the present Moon is a mixture of Theia and the early Earth.”
Though more research is needed to confirm this possibility, Herwartz stated that it could be “30 to 50% of the moon was once part of Theia.” Speaking to the BBC recently, Herwartz stated that “the giant impact hypothesis” as to how the moon was formed when another planet collided with Earth has now been confirmed.
If Earth’s moon was really formed as a result of a collision with anther planet, as this recent re-evaluation of the three lunar rocks suggests, the planet or possibly large meteor that smashed into ours was probably one that was roughly Mars’s size.
Besides the rather dramatic idea that the moon was created as a result of an ancient collision between Earth and another planet, there are other theories that might explain the difference in the levels of oxygen-17 between the lunar rocks and Earthly ones. For example, a hail of comets smashing into our planet could have caused Earth’s oxygen chemistry to have been changed enough to account for the subtle difference. Scientists may never know with 100 percent certainty how the moon was formed, but the re-analysis of the three lunar rocks by scientists from Germany has helped add validity to the giant impact idea.
Written by: Douglas Cobb