Using moon rock samples gathered from the Apollo missions more than 40 years ago, German scientists say they've finally found evidence that confirms the moon was created in the wake of a cataclysmic collision between Earth and an ancient planet known as Theia some 4.5 billion years ago.

For decades, the theory, known as the giant impact hypothesis, has been the most widely accepted explanation for the moon's formation. The hypothesis holds that the collision between Earth and Theia, an ancient planet theorized to be roughly the size of Mars, ejected debris into space, which eventually coalesced into the moon we know now, according to National Geographic.

But despite support from models and computer simulations, scientists still lacked physical proof of Theia's existence. Early analysis of moon rock only turned up chemical traces of Earth, which is key, because scientists believe that each planet has a unique chemical composition, similar to a fingerprint, NBC reports. So, if the moon was created out of material from both Earth and Theia, two different chemical signatures should be present in moon rock samples.

"If the moon formed predominantly from the fragments of Theia, as predicted by most numerical models, the Earth and moon should differ," the study, led by Daniel Herwartz from the German unviersity of Georg-August-Universität Göttingen, said. "But we have now discovered small differences between the Earth and the Moon. This confirms the giant impact hypothesis," Herwartz told the BBC.

Now, thanks to advances in technology, Herwartz and his team say they've been able to discern minute differences in oxygen atoms in moon rocks, which they say serves as evidence of Theia's chemical makeup. As National Geographic notes, the evidence is extremely limited, to the tune of just 12 parts per million more of a certain kind of heavier oxygen atom—an isotope known as oxygen-17.

Based on that data, Herwartz believes that the moon is made up of roughly 30 to 50 percent of material from Theia.

However, as the BBC points out, some planetary scientists aren't buying the news.

"What you are looking for is a much bigger difference, because that is what the rest of the Solar System looks like based on meteorite measurements," Professor Alex Halliday of Oxford Universitytold the BBC.

Halliday and others believe there should be a much greater difference between the chemical signature from material from Theia and Earth, more in line with the differences between the chemical makeup of material currently found in our solar system.

On a much more basic level, others are skeptical because the data was derived from just three lunar rock samples.

"We have to be cautious about the representativeness of these rocks of the entire Moon, and so further analysis of a variety of lunar rocks is required for further confirmation," Dr. Mahesh Anand from Open University told the BBC.

Skepticism aside, if Herwartz and others can build off this initial data, we could be that much closer to understanding exactly how our moon, and other extra terrestrial bodies, came to be.

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Total eclipse of the moon underway over southern California as seen from Korea town ,west of downtown Los Angeles, early on April 15, 2014. (Desiree Martin/AFP/Getty Images)