50-year-old mystery of Earth’s magnetosphere solved

50-year-old mystery of Earth's magnetosphere solved

Waves created by solar winds seem to mysteriously escape the region formed by our planet’s magnetosphere. After 50 years, scientists have finally discovered how this happens: in fact, these waves are clones of the original ones.

  • Mechanism behind solar wind may be in ‘blind spot’ region
  • Solar storms create cracks in Earth’s magnetic field

When the solar winds reach our planet, Earth’s magnetic field protects the planet from charged particles from the Sun. During the process, electromagnetic waves appear in telescopes as small oscillations in the Earth’s magnetic field.

The waves can cause some problems for our planet, such as accelerating particles until they reach high energies, transforming them into threats to electronic systems in Earth orbit and to communication signals. Observatories on the Earth side facing the Sun often record these complex oscillations and reveal a relationship between waves from different regions.

One of these regions is known as a “shock” and forms from the interaction between the Earth’s magnetosphere and the supersonic solar wind sent to Earth. The shock serves to divert the flow of the solar wind and creates a jolt full of potentially dangerous electromagnetic waves. On the other hand, solar storms hit another region, called the “ante-shock”.

The mystery that troubles scientists is that the fore-shock waves can apparently propagate to the other side of the shock. Since the 1970s, scientists have believed that there is a connection between the two wave propagations and that waves from the fore-shock can enter the Earth’s magnetosphere, traveling all the way to the Earth’s surface.

To confirm this hypothesis, however, scientists needed to demonstrate how the waves pass through the shock region, and to date no evidence has been found that this can happen.

In new research, scientists created simulations that proved consistent with observations. After three years of study, they discovered that the waves do not go through the shock, but are cloned. “The waves we saw behind the shock were not the same as those in the fore-shock, but new waves created by the periodic impact of the fore-shock waves on the shock.”

This is because the shock region is compressed and heated by the solar wind, while the fore-shock waves tune in to the shock. As a result, the solar wind behind the shock shifts and creates new waves, along with those in the fore-shock, giving the impression that they travel from one region to the next.

The study was published in the journal Nature Physics.

Source: Nature Physics, University of Helsinki