After almost five decades since the Apollo program, scientists are still gaining new insights into the Moon.
Researchers have long been interested in decoding one of the mysteries of the Moon: its magnetic field.
While the Moon today lacks an internal magnetic field, it has a couple of magnetic spots. An unknown that frustrates scientists to this day is to what extent the Moon’s magnetic field once was. Or did it have any connection to Earth’s powerful magnetic field created by swirling liquid iron in the planet’s core?
Recently, a team of scientists, with the help of an Apollo 17 astronaut, learnt something new about the strength and shape of the lunar magnetic field. Spoiler alert: It may have resembled Earth’s!
The Moon is full of surprises.
Working with researchers from the University of Oxford, Massachusetts Institute of Technology, Utrecht University and Albert-Ludwigs-Universität Freiburg is Apollo 17 astronaut and geologist Dr Harrison Schmitt. He was also the first scientist and last human to set foot on the Moon! Together, they scrutinised a few Apollo-era samples and combined the data with recent NASA images of the lunar surface to unveil the secrets of the Moon.
Published in the journal Nature Astronomy, the international team of researchers worked out the field angle of the Moon’s ancient magnetic field from the lunar samples and juxtaposed their findings with earlier predictions.
To their surprise, the researchers discovered that the Moon’s magnetic field actually operated like Earth’s — with a North and South pole. Since the lunar core is much smaller than Earth’s, it’s astounding that the Moon had a magnetic field at all.
Besides the similarity in the magnetic field, the Moon’s field strength may have also been as strong as Earth’s. For a planetary body that has a core of only 1 – 3% of its total mass, the Moon’s field strength may have averaged around 50 microTeslas. In comparison, Earth’s core is about 33% of its total mass, but its field strength is only 25 – 65 microTeslas.
But why does it matter?
Understanding the Moon’s ancient magnetic field allows scientists to further comprehend how, why and when planets generate magnetic fields.
Deciphering magnetic fields can also enable scientists to make sense of the relationship between magnetic fields and life, as we know it. Since a magnetic field is thought to be an essential ingredient for a habitable planet, learning more about our natural satellite could help diagnose why Mars lost its own. And do we need to jump-start the Red Planet’s magnetic field so that humans can terraform it one day?
But this study has also posed more questions: How did a planetary body so small (compared to Earth) generate such a strong magnetic field? And what made it stop? And what implications did that have on ancient Earth?
Perhaps future Moon missions will uncover the enigma that is the Moon and unlock a scientific bonanza for astronomers all over the world.
