Researchers have detected fluctuations in Earth's magnetosphere created by the same tidal forces that the moon exerts on the oceans.
© Chinese Academy of SciencesAn illustration comparing the moon's impact on ocean tides (blue) with its impact on plasmasphere tides (orange).
In the study, published Jan. 26 in the journal
Nature Physics, scientists used more than 40 years of data collected by satellites to track the minute changes in the shape of the plasmasphere, the inner region of
Earth's magnetosphere, which shields our planet from solar storms and other types of high-energy particles.
The plasmasphere is a roughly doughnut-shaped blob of cool
plasma that sits on top of Earth's magnetic field lines, just above the ionosphere, the electrically charged part of the upper atmosphere. The plasma, or ionized gas, in the plasmasphere is denser than the plasma in the outer regions of the magnetosphere, which causes it to sink to the bottom of the magnetosphere. The boundary between this dense sunken plasma and the rest of the magnetosphere is known as the plasmapause.
"Given its cold, dense plasma properties, the plasmasphere can be regarded as a 'plasma ocean,' and the plasmapause represents the 'surface' of this ocean," the researchers wrote in the paper. The moon's gravitational pull can distort this "ocean," causing its surface to rise and fall like the ocean tides.
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