Earth’s magnetic field controls space weather, shields us from solar wind: new study

Researchers in the Faculty of Science have made an important contribution to new findings about Earth’s magnetic field and its role in shielding our planet from solar wind, the continuous stream of charged particles emanated by the sun.

In the discovery, published in Nature Communications, a team of Alberta-based scientists found that electromagnetic energy originating in the solar wind shows a clear preference to head toward Earth’s northern polar regions rather than their southern counterparts.

The new findings suggest that, in addition to acting as a shield from incoming solar particles, the magnetic field also actively controls how the energy is distributed and channeled into Earth’s atmosphere.

International research collaboration helps yield new discovery

Using information from the European Space Agency’s (ESA)’s Swarm satellite constellation, researchers in the University of Alberta’s Department of Physics analyzed data from electric field instruments (EFIs) designed and operated at the University of Calgary by a team led by Dr. David Knudsen, PhD, and Dr. Johnathan Burchill, PhD, both in the Department of Physics and Astronomy. Lead author Dr. Ivan Pakhotin at the University of Alberta and co-authors at both universities discovered the "surprising" imbalance in how Earth’s magnetic field responds to space weather driven by the sun.

The high-calibre international partnership between the two universities and the ESA reflects the research excellence in space science in Alberta. The University of Calgary has been Canada’s most prolific university-based provider of space instrumentation, with more than 20 instruments developed and launched into space over the university’s 50-plus-year history, according to Knudsen.

While the terms “North Pole” and “South Pole” conjure images of polar bears and penguins, they refer to the north and south poles of our planet’s magnetic field, and loosely line up with Earth’s rotational axis. Earth’s magnetic field is visible in action when the aurora borealis — or northern lights — appear in the northern night skies, the result of its interaction with charged atomic particles from the sun.

While the dancing ribbons of light are a beautiful sight, they’re representative of a constant bombardment of charged particles in the solar wind, and can have significant impacts on some of our most important systems like communication networks and navigation systems (like GPS and satellites). In severe cases, solar storms can cause communication and electrical systems and even satellites to fail.

“Because the south magnetic pole is further away from Earth’s spin axis than the north magnetic pole, an asymmetry is imposed on how much energy makes its way down toward Earth in the north and south,” explains Pakhotin, the paper’s lead author and postdoctoral fellow in UAlberta’s Department of Physics.

While researchers aren’t yet sure what the effects of this asymmetry might be, the findings suggest that it could also point to an asymmetry between the aurora australis in the south and the aurora borealis in the north. Further, they suggest that the dynamics of upper atmospheric chemistry may vary between the hemispheres, particularly when geomagnetic activity is strong.

UCalgary contribution to Swarm satellite constellation essential to new findings

Knudsen and Burchill specialize in near-Earth space research, and have extensive experience in the development of space instrumentation. Knudsen serves as lead scientist for the EFIs on the Swarm satellites; Burchill has responsible for their operation since launch in 2013.

Each EFI contains two sensors known as thermal ion imagers. Initially developed at UCalgary with support from ESA and the Canadian Space Agency, and built by Ontario-based COM DEV Canada (now Honeywell), the thermal ion imagers use the same technology used in digital cameras — CCD detector technology — to detect charged particles. The sensors then produce precision measurements of ionospheric winds and temperatures. “This information is used to calculate the electric field, an important counterpart to the magnetic field,” Knudsen explains.

Understanding Earth’s electric and magnetic field environment helps scientists design better electrical grids and early warning systems when solar disturbances like mass coronal ejections or solar storms occur and affect Earth. However, the primary motivation of this research is to understand the fundamental behaviour of the charged-particle gases (plasmas) surrounding Earth, and the causes and consequences of the northern and southern lights, key aspects of which remain unexplained. 

Swarm’s three satellites return information about how the magnetic field protects Earth from the dangerous particles in solar wind, along with how the field is generated and how the position of Earth’s magnetic north changes over time.