Giant Impact Theory May Not Be Entirely True, Study Suggests

Scientists have proposed that the Moon that people see today was not formed as suggested by the "giant impact theory." The new hypothesis suggests that several moonlets formed after a series of collision with Earth fused together to form one Moon.

The explosive Moon birth theory was proposed recently by Raluca Rufu, a planetary scientist of Weizman Institute of Science, Israel. Rufu was trying to find an answer for the anomaly that prevails in the giant impact theory.

The theory suggests that millions of years ago, Earth faced a massive collision with a passing planet like a celestial body, most probably the size of Mars. The impact knocked off Earth about 23-degree from its axis, which is still true and blasted off debris into space. The debris cloud led to the formation of Moon, TIME reported.

Computer simulations indicate that, if one giant impact led to the formation of Moon, then the debris cloud from which it was formed should be made up of 70 percent impactor material, i.e., the passing planet like object, and the rest that is 30 percent should be the debris formed from Earth, which does not hold true.

The lunar samples collected during the Apollo landing missions were analyzed on Earth and it was found that the nature and proportion of isotopes of oxygen, titanium and tungsten present in lunar rocks matches with that of the rocks obtained from Earth.

Furthermore, principles of physics also defy the possibility of formation of enough amount of debris required for the formation of the Moon as a result of a single cosmic collision. The study done by Rufu and her team involved running thousands of computer simulations by varying the size of the impactor body and the number of collisions that could have possibly given rise to a Moon like an orbiting celestial body.

Space.com reported that around 20 impacts are required to generate the amount of debris required for the formation of the Moon. "The multiple-impact scenario is a more natural way of explaining the formation of the moon," Rufu said. "In the early stages of the solar system, impacts were very abundant; therefore, it is more natural that several common impactors formed the moon, rather than one special one," she added.

The study made by Raluca Rufu and her team was published in the journal Nature and challenges the previously accepted giant impact theory of formation of the Moon.