Thanks to new data obtained by NASA’s Acceleration, Reconnection, Turbulence and Electrodynamics of the Moon’s Interaction with the Sun mission – better known, happily, by its acronym ARTEMIS – scientists are closer to understanding why the moon’s surface exhibits light and dark patches.
It’s all down to the effects of the solar wind – the continuous outflow of particles and radiation that bathes the entire solar system.
The wind is magnetised, which means it is largely deflected away from the Earth, because the planet has its own magnetic field.
The moon does not enjoy such protection. However, certain rocks scattered about the surface do have magnetic properties and manifest miniature fields – magnetic bubbles, in effect – which shield the immediate environment from the worst of the sun’s output.
“The magnetic fields in some regions are locally acting as this magnetic sunscreen,” says Andrew Poppe, a scientist at the University of California, Berkeley, who researches the moon’s crustal magnetic fields using data from ARTEMIS.