
© E. Masongsong/UCLA, M. Archer/QMUL, H. Hietala/UTUArtist rendition of a plasma jet impact (yellow) generating standing waves at the magnetopause boundary (blue) and in the magnetosphere (green). The outer group of four THEMIS probes witnessed the flapping of the magnetopause over each satellite in succession, confirming the expected behaviour/frequency of the theorised magnetopause eigenmode wave.
The Earth's magnetic shield booms like a drum when it is hit by strong impulses, according to new research from Queen Mary University of London.
As an impulse strikes the outer boundary of the shield, known as the magnetopause, ripples travel along its surface which then get reflected back when they approach the
magnetic poles.
The interference of the original and reflected waves leads to a standing wave pattern, in which specific points appear to be standing still while others vibrate back and forth. A drum resonates like this when struck in exactly the same way.
This study, published in
Nature Communications, describes the first time this effect has been observed after it was theoretically proposed 45 years ago.
Movements of the magnetopause are important in controlling the flow of energy within our
space environment with wide-ranging effects on space weather, which is how phenomena from space can potentially damage technology like power grids, GPS and even passenger airlines.
The discovery that the boundary moves in this way sheds light on potential global consequences that previously had not been considered.
Dr. Martin Archer, space physicist at Queen Mary University of London, and lead author of the paper, said: "There had been speculation that these drum-like vibrations might not occur at all, given the lack of evidence over the 45 years since they were proposed. Another possibility was that they are just very hard to definitively detect.
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