Artistic vision of the impact of a plasma jet (yellow) generating standing waves at the boundary of the magnetopause (blue) in the magnetosphere (green). An external group of four probes from THEMIS recorded a sequential oscillation of the magnetopause under each satellite, confirming the expected frequency of the theoretical wave.
The new study showed that the magnetic shield rattles, like a drum, when it is influenced by strong impulses. When the pulse hits the outer boundary of the magnetopause, the ripple moves along its surface and is reflected when it approaches the magnetic poles.
The intervention of incoming and reflected waves leads to the formation of a standing wave pattern, where individual points appear fixed, while others vibrate back and forth. The drum also resonates on impact. This effect was first observed after a theoretical presentation 45 years ago.
The movements of the magnetopause are important for controlling the energy flow in a space environment with a wide influence on space weather, which can damage electrical networks, GPS and passenger airlines. A new study allows us to take a broader look at global consequences that were not previously taken into account.
For many years, scientists have assumed that these drum vibrations may not appear at all, because for 45 years since the inception of the theory, no one has provided evidence. But some thought that these vibrations were simply extremely difficult to find. The earth's magnetic shield is constantly confronted with turbulence, so the researchers thought that for clear evidence you need to find a sharp impulse event. In addition, you need to install several satellites at certain points to eliminate other interference.
Scientists used a group of 5 satellites THEMIS, which recorded the impact of a powerful isolated plasma jet into the magnetopause. The probes were able to detect border oscillations and the resulting sounds in the earth's magnetic shield. All this was consistent with the theory and allowed to cross out other explanations.
Many impulses come from the solar wind and are considered the result of its contact with the magnetic field of our planet. As a result, this interaction creates a magnetic shield of the planet, bounded by a magnetopause, which protects us from a large amount of cosmic radiation.
Mercury, Jupiter and Saturn also have similar magnetic shields, so it is likely that it will be possible to find drum vibrations in other worlds. Further studies will help to understand how often vibrations occur on Earth and whether they are on other planets.