Lunar vortices are beautiful optical anomalies on the surface of the moon that occur without any definite shape and exist in different sizes. These particular delights intrigued scientists who tried to understand their exact original story. Scientists at Rutgers and the University of California at Berkeley have now investigated the origin of these anomalies and are coming back with a new insight into the history of the moon.
Advertisement – Continue reading below
The most famous lunar vortex is Reiner Gamma. About 40 miles long and visible through most telescopes on a clear night, this is a popular place for backyard astronomers.
Like many lunar vortices, Reiner Gamma has powerful localized magnetic fields. Scientists believe that the patterns of shine and darkness that mix with Reiner Gamma come from magnetic fields that deflect particles from the solar wind. Over an extended period of time, this deviation would cause some parts of the lunar surface to slow down more slowly.
"But the cause of these magnetic fields, and therefore whirls themselves, has long been a mystery," says Sonia Tikoo, co-author of the study recently published in the newspaper. Journal of Geophysical Research – Planets and an assistant professor at Rutgers, in a press release. "To solve it, we had to determine what type of geological feature could produce these magnetic fields and why their magnetism was so powerful."
The researchers examined the geometry of lunar vortices. From there, they constructed a mathematical model on the idea that each vortex was above a narrow magnetic object. Thanks to this model, they found an image compatible with the appearance of lava tubes and lava dikes. Lava tubes are long, narrow structures flowing lava through volcanoes, while lava dikes are vertical magma sheets injected into the lunar crust. These are known geological features, but are generally not considered magnetic.
Advertisement – Continue reading below
On Earth, volcanoes have many destructive qualities but none is due to magnetism. Studies carried out in 2009, using samples brought back from the first lunar landings of the 60s and 70s, showed that lunar rocks had a history of magnetism.
The melting heart of the moon may have at some point created its own magnetic field, and the rocks at the surface still share some of these qualities. Break down certain types of lunar material with enough heat and, at the right temperature, they will release metallic iron. With a sufficiently strong magnetic field nearby, the iron would become magnetized in that direction.
This would not happen on Earth, where floating oxygen binds to iron. Scientists say that this would not happen on the moon either, because there is no longer any global magnetic field. However, last year, Tikoo also discovered that the moon's historical magnetic field actually was 1 billion to 2.5 billion years older than expected.