Influenced by a constant stream of charged particles from the solar wind, Earth is not without its protection. Our planet is wrapped in a bubble of magnetism called the magnetosphere, which oozes out from inside the planet’s interior.
As the solar wind blows, scientists assumed that energy in the plasma at the edge of this bubble would ripple in a series of waves, generated by the interaction between the solar wind and the magnetosphere, the direction in which the wind is blowing. But now they have discovered a surprise: some of the generated waves remain stationary.
Space physicist Martin Archer of Imperial College London has been exploring the limits of Earth’s magnetosphere for many years.
“Understanding the limitations of any system is an important problem,” he says. “That’s how stuff gets in: energy, momentum, matter.”
Recently, Archer and his colleagues found that the boundary of the magnetosphere, called the magnetopause, behaves like the membrane of the drum: strike it with a pulse from the solar wind, and the waves, called magnetosonic waves , expands towards the poles with the magnetopause. , and is reflected back towards the source.
Now, using data from NASA’s Time History of Events and Macroscale Interactions During the Substorm (THEMIS) mission, a team of researchers led by Archer has discovered that, not only do these magnetosonic waves bounce back, they can travel against. solar wind.
So what happens when these waves encounter the opposite wind? According to modeling done by the researchers, both forces can reach an impasse, in which the push of the solar wind cancels the push of the wave. A lot of energy is being applied, but nothing is going anywhere.
“It’s like trying to walk down an escalator,” Archer says. “It will feel like you’re not moving at all, even if you’re trying hard.”
Since these standing waves stay longer in the Earth’s magnetosphere, they can have a more significant effect on particle acceleration, which in turn affects Earth. We know that plasma waves have an accelerating effect on electrons, which can “surf” the plasma waves like the wakesurfer uses to accelerate water waves.
Particles moving with the magnetic field toward the poles are responsible for the gorgeous auroras that light up our skies (as well as communication problems in the ionosphere).
Earth’s radiation belts confined by the magnetosphere may also be affected. More research will be needed to understand how these standing waves affect particle acceleration.
Meanwhile, the researchers also translated standing waves into sound. Archer and his colleagues have done this before, translating the sounds of the magnetopause’s drum-like reactions into the solar wind.
It’s not just a fascinating thing to experience; Translating space data into a different medium could help scientists reveal information that would otherwise have passed us by.
“While in a simulation we can see what’s happening everywhere, satellites can only measure these waves where they’re just giving us time-series, quirky lines. This kind of data is actually our ability to hear visually. Emotion is best suited, so listening to data can often give us a more intuitive idea of what’s going on,” Archer explains.
“You can hear the deep breathing sounds of standing surface waves persist throughout, increasing in volume as each pulse hits. The high-pitched sounds associated with other types of waves don’t last nearly as long. “
research has been published in nature communication.