More research into the mysterious core of the moon is required to understand its structure and origins. Proof and analysis of the existence and functioning of the dynamo that caused a magnetic field needs to be found according to scientists. These insights could further aid the discovery of other habitable worlds in the galaxy.
According to Sonia Tikoo, a postdoctoral researcher at UC Berkeley, a planet’s long-lived, strong magnetic field is key to shielding life from damage from harmful solar particles. Only a strong and effective magnetic field can support habitation. Tikoo and Benjamin Weiss, a professor of Planetary Sciences at M.I.T. recently published a paper in the Science journal, which analyzes gathering evidence of the magnetic field and possible explanations for its surprisingly long-lived magnetic field.
The first lunar rocks brought back by the Apollo missions were analyzed and their magnetized properties were revealed. But whether this was the result of the moon’s own magnetic field, or a signature imprinted upon surface rocks by an external planetary event was uncertain.
New analyses of these rocks strongly points to evidence that Earth’s only satellite indeed had a magnetic field, which was the result of an ancient core dynamo action. Furthermore, that field was also unusually long-lived, lasting over a billion years, until its demise at least 3.5 billion years ago.
Whether the moon had a core dynamo is no longer debated. Scientists now seek answers about how this magnetic field existed for so long. A popular theory about the origin of the moon is that it resulted when matter the size of Mars collided with early Earth. However, it is unlikely that the heat generated could have caused the core to keep gyrating as long as the magnetic field now appears to have lasted.
Scientists constantly theorize on forces that may power the dynamos that keep planetary magnetic fields in existence. The moon’s magnetic field could have been powered in a manner similar to that of Earth. This process is known as geodynamics – the rotation and convection of complex electro-magnetic fluids at the center, converting the planet into a massive dipole magnet.
Perhaps the gravitational pull of the Earth on the surface of the moon caused it to contra-rotate and power the dynamo at its core. Maybe the lunar magnetic field was generated by a liquid metallic core. Possible convection currents generated by the crystallization of the inner core could also have created the magnetic field. This was probably massively forceful, uniquely active, and stronger than the Earth’s. All said, the moon continues to hide the mysteries at its core.
Weiss’s theory is that simply discovering the factors and timelines that caused the dynamo to switch off would lead to understanding how it was originally powered. The answers could also accelerate the search for life in worlds beyond.
The ongoing quest raises many questions and no definitive answers as yet. However, there is consensus now among experts that the moon did have a dynamo at its core that powered its magnetic field, lasted for billions of years, and mysteriously stopped several billion years ago.
By Bina Joseph
Photo by Bryan Jones – Flickr License